Thank you!
I started with a very basic outline of all the chapters and arcs (see an above post for an example of what Ch. 6's first outline looked like). When I get to a chapter I break it down further into strips. Then when I get to the strips I write out more specific scripts. These read like a play, with dialogue and stage direction. Sometimes I go through multiple re-writes of scripts before I ever start the art. The art part takes a while so I want to be confident in the script early on. As for the overall thing, you just have to do the best of your ability at the time. Some things might not work out as planned but you can't fret too much or the comic will never be finished.
I think the main thing when you're starting out is don't get discouraged. Art and writing is hard to do. Like the saying goes, you have to make a ton of crappy stuff before you get to the better stuff. Put in the hours and you will see definite progress over time. And if you find that it isn't for you, it's okay to try out other pursuits. It can be hard to do, but don't link your self-esteem to likes/favs/page views. It's nice to have the support of others, but it's not what will sustain your interest. Being genuinely interested in your project is the way to go and will keep you coming back.
Best of luck to you with your projects!