A few things should be noted first:  I have a major in creative writing; I seriously have OCD (and it sucks), and I'm crazy with details and inspiration. 

With that out of the way, I have been asked before (on other forums for now, but maybe on this one in the future) how I come up with some of my characters.  For some people, it is very easy.  They get an idea, spend a couple of hours developing it, and boom... finished product.  For me, it can be a little more complicated (read that as a lot more complicated). 

First off... I don't really worry about names.  They usually come together during some point of the creative process or either they come about at the very end.  This can be a major deviation from what a lot of people are used to.  How can you work on something that you don't have any way to identify?  I guess my brain is both detailed AND abstract enough to be able to make this work somehow.  But I either start off with a vague idea or a vague image.  Those are usually my two starting points.

To flesh out an idea, I usually go to my wonderful roots in table top roleplaying.  Don't know how many have heard of it, but yes, MLP did have a fandom made table top game called Roleplaying is Magic.  Even though I've found RiM sheets don't work very well online, I still like to have a firm set of numbers to play around with so I can use it later to use for comparison.  It sort of helps me be like "Alright, is this pony someone who is going to get physically exhausted after a run or is thing in my head bordering on Iron Pony strength?  It also keeps me from too off track in my creation process.  Sometimes I'll get to focusing too much on one thing so I try to spent about 15 minutes on each part (Design, Aspect, Statistics, Headway) in the beginning. 

Race is usually the very first thing that comes up (if it hasn't already).  Age also is pretty much a given since there is no real "age" in MLP.  I mean sure: baby, foal, "standard", and elderly.  One could always argue that the Sassy Saddles, Celestia, Luna, Cadence type are mature adults... but to me, that is a little mix of age AND body type.  I mean, think of Fluttershy's parents.  They certainly don't have that look and they're old enough for two kids.  Sassy Saddles isn't a princess but she shares their body look.   In the show, age also comes with traits of maturity rather than a number.  I peg the Mane 6 as in late teens to mid 20 somethings with Pinkie Pie and Fluttershy being the youngest.  Pinkie has very little sense of responsibility; Fluttershy hasn't doesn't seem to have been out in the "real world" to build up much self-confidence.  So I sort of go by, "What all have they accomplised up to the starting point?
What are some of the things they are good at (not specifically cutie mark talent unless it is one of those things that was sort of in the idea at the beginning)?  How do they "earn their keep" so to speak?  Currency is rarely shown but it does exist... but not in the money making sense but more of they need something to do rather than sit around being lazy.  Hobbies < Skills < Talents < Special Talent.  Where were they born, have they moved/been anywhere, where are they living now?  What is their personality?  What are some of their goals (I usally go with Short, Mid, and Long Range timetables)?  What is the general direction I have in mind for them?

The above may sound like a lot but remember what I said before, it is something you can ALWAYS go back to if you feel like it needs more fleshing out and I like to keep it very simple in the beginning... like just a bullet point list of answers.  Plus, you don't want to write yourself into a hole.  If you are going to be using them to RP with, or even a damn book of your own later down the line, you don't want to end up contradicting something you already established.  It hasn't happened with pony things, but other fandom RP sites I've been a part of that require you to come up with a character, I left myself almost no room for growth either way... just interactions.  And while that is perfectly okay, what makes a character compelling are the subtle changes and development over time.  Trust me on this one.  I've been on sites where you only need one or two paragraphs to needing at least a 1,500 word bio for someone who is supposed to be about thirteen.

Then I spend some time thinking about general look.  You know how the ponies in General Zoi Creators are start out with the same basic colors?  I don't know if in my lack of artistic talent I have just used them so much that it becomes all I see or if I learned that colors end up getting a lot of work on their own so it is better to just pick three or four basic (I try to stick with just mane/tail, body, eyes at the beginning) ones to start out with and come back to it later.  What type of mane/tail style do I want them to have?  Long or short, straight or curly, do they wear it any certain way?  Again, for now, keep it simple.  You can go into detail later in the "polishing" phase.

Next I move on to their Cutie Mark.  At first it just seems like some more personality development but I do try to keep them separate.  Unless I'm creating a character with its own... thing, I really like to go back to Roleplaying is Magic for this one.  They use this thing called Guiding Elements.  I like to take it a step farther and give them their own "Aspect" of Harmony.  What is the ONE word that I would use to describe the force that guides most of their actions?  A quick throw back to the basic outlining stage, if during some point of this, you haven't come up with a "Fatal Flaw", do it now.  And I'm not talking about flaws in like "Oh, she's scared of spiders."  I'm talking about flaw as in bad habit of personality.  Like... I'll use a few of the Mane 6 for examples.  Rainbow Dash might be loyal to her friends, but she lets her pride get in even their way at times.  She is boastful and sometimes a little too arrogant for her own good and even though she might not mean anything by it, it could lead to hurt feelings in others.  Twilight is so worried about lists and doing things by the book, she doesn't give people enough room to be themselves.  Applejack can let her industriousness get in the way of just relaxing.  These things happen time and time again in all different sorts of situations.  It is so deeply ingrained into their brains, that even though it can be useful, it leads to bad stuff happening more often than not.  But back to the cutie mark.  I actually like throwing these things into to the design of it (maybe a nod to symbolic meanings of colors) and the story of how they got it.  An example of this would be Fluttershy's cutie mark of butterflies but her talent is animals.  I see butterflies, I don't think kindness.  I don't think of all sorts of other animals.  I think of gentleness, delicacy.  Both of which could be considered part of her Element of Harmony, but at the same time (and maybe this is just me overthinking things) go back to her fatal flaw of being too timid, too "delicate" and too soft spoken for her own good.  Again, since I totally suck with art of my own, yay for words!  I keep it simple to give myself wiggle room in this department later down the road... to me... all of the above go into the "development of an idea" phase and leads into the next part, that can be flip flopped if you start off with a vague image in mind.

So, sometimes you start off with a visual image in your head.  You see the pink pegasus, with bows and braids, who has a storm cloud for a cutie mark who creates lightning.  You already have the visual part down and you just need the details.  But for me... the visual idea is the one that usually ends up backfiring.  The first things that pop in my head are usually the things that I've seen done most often, sometimes to the point of to death.  Maybe that's the reason I've just started seeing my ponies as the brown, standard stance, simple mane/tail style. But this point is where the tweaking, color schemes, and all that comes into play!

The most important thing for me is to try to do something that hasn't been done much before, if at all.  To guard against it, I follow pick at least four images to pull color schemes from: a piece of artwork that you feel is your "character in art" (and art doesn't just have to be a van Gogh piece hanging in a museum, it can be a digital piece from an amazing artist on DA, a comic book page.  For example, I used Neil Gaiman's character Delirium as my inspiration for Willow Wisp), something from nature that relates to the pony's talent (in either photo, digital media, or traditional artwork form), an anime or manga image (anime girl with silver hair, or anime girl with flowers.  Anime and manga pieces tend to use more vibrant colors where as other pieces of art and/or photographs might not, and finally the image that I end up using as basis for their cutie mark (because more often than not, the colors of the cutie mark are incorporated into a pony's colors). 

I take all four images and run them through this wonderful little tool called Chip It by Sherwin Williams.  It creates a color palette of all the paint colors they carry that best compliments the image.  The basic image will give you five colors but I always go to the "Edit Colors" option.  It gives you ten colors rather than five.  You have to think, I use Chip It for a totally different purpose than it was created.  It's made to, y'know, paint rooms with so you're going to get a lot of "Highly Reflective White" and "Tricorn Black".  The other colors are the colors that compliment the image.  I make a list of all the colors that come up.  More than likely, you'll see some repeats of the same colors unless everything you chose were just totally not related at all.  I grab any that were repeated multiple times and maybe two or three of my favorites.  Maybe a couple of others for "back ups".  Unfortunately, Chip It doesn't give you color codes.  So I download the ones that had repeated colors and my other colors then head on over to Get Colors From Image and snag the hex code.  (Some programs and sites use RGB codes instead, and if that happens for whatever reason you can use Hex to RGB to convert it.)

If I'm feeling just super lazy, I head over to a site called Colour Lovers and grab a pre-made basic color palette.  Though, this rarely happens.  The insanity described above is what usually happens. 

Then, again being I totally suck at art, I head on over to good ol General Zoi and actually use both of the pony creators.  The older one to see what the cutie mark looks like with the color scheme and the newer one for poses.  I dislike a lot of the mane/tail styles on the newer one, even though there are a couple I like but I find myself using the same ones for almost all of the images I come up with.  I save the image and the pony code for my own reference or so I can give it to others down the line.  Then I hop on over to my other genator image, Pony Lumen 3D to work on shading colors.  Manes and tails are limited but you can check out some different effects which I like.  It is also good for different eye styles and the changeling shell.

Either during the General Zoi/Pony Lumen process (or base process which comes in a little bit) I'll end up using Paletton to maybe tweak some colors.  General Zoi sticks you with its own outline color based on the color code but it may look better with something else, or you may want three main colors, or more choices for accessories so I use it a lot more in the base process.  Pony lumen has no outline but does allow for some shading and gradients options.

After I have the color scheme pretty much down, it is back to the Google Image search where I do admit to shamelessly snatching up two or three mlp images (either ponies in the show or OCs) for better looking mane/tail styles.  I play around some to see if I can either sketch them out myself or break it down in an image editor to use bits and pieces of to come up with something similar but not a totally blatant rip off.  You can also find some pretty decent looking styles and line art guides on DA.  I'm still not great at them, but it has helped IMMENSELY.

I usually stay on DA where the search for a base in a pose I think fits well comes next.  At which point, I try to pull something decent look off using a mix of using mainly GIMP but I have started playing around with Paint.NET and Inkscape.  Luckily, I have a hybrid tablet/laptop so I can do some touch screen "drawing" rather than just relying on mouse work and a very unsteady hand.  But I don't know if it is just GIMP being a resource hog, pressure sensitivy, some crazy setting I don't know about or what... but I even have issues with that sometimes when trying to actually put on the mane and tail.  It doesn't always line up right or there is a long delay.  So sometimes, the base images come out looking almost as bad as the generator images.

Then comes the finishing touches.  Going back to the development and adding in the details and connecting the dots in that bullet point list mentioned above.  By now I have a good bit of the character and images already fleshed out in my head so just getting it down takes about thirty minutes or so.  Maybe a little longer depending on their level of complexity.  And by the end of it, I have a long winded character sheet and three or four images I can give to an awesome artist for a comission piece.