I wouldn't exactly qualify myself as "experienced" but here are some "tips" I think will be most helpful for you.
Grab some reference shots! We don't know exactly how every single thing is built, nor do we know how every curve flows on an object. It's important to grab something you want to draw, study it and then try to replicate it. You may think of this as cheating, but if you go to ANY drawing class, you'll most likely be drawing the objects straight in front of you. This leads to my next suggestion...
Draw from life! Now you may think of this as being counter productive, but it's an incredibly important thing to learn my friend! Sure, we could grab an image from the net, but this flattens the object and you loose a great deal of learning how light and shadow forms on an object. Chiaroscuro is a vital thing to learn if you wish to lean towards adding value to your illustrations. Besides, something tells me you don't want to be drawing ponies forever based on what's on your DA.
READ A BOOK, TAKE A CLASS! This is the most difficult thing to do I believe, because this takes quite a chunk of willpower to do. You could purchase a drawing book, but you'll most likely need to do the exercises and go through the book several times over before it sticks. Even if you enrolled into a class, you'll need to actually draw outside of the class to really acquire the full potential of what you can get out it. To be honest though, most high school art classes will be meh quality. Of course, the last time I took a high school class was YEARS AGO, so it could have changed for the better. Either way, I'd suggest waiting for College.
DRAW AT LEAST ONCE A DAY! Out of everything I've said in this wall of text, you should at least draw once a day to help further improve yourself. It will not only help further increase your understanding in the medium of choice, but it'll also help prevent getting rusty and keep your 'drawing limbs' in shape. It doesn't need to be anything complicated, it could be a box, a pony, or a box pony! Now, why on earth would you want to draw something as simple as a box? Well, think about it, do you REALLY know how to draw a box? Lets say you do, do you know how to make it look more on the realism side? How would you make a convincing box which was hollow on the inside? Even if you mastered the box, do you know how every medium will react? What about pen versus charcoal, pastel versus coloured pencil? You get the point, there's so many things you may not think of where a simple little doodle can help you further understand what you're drawing.
Alright, I think that's enough text for now. My throat's parched and all I did was type the bloody thing! I'll just take my leave here, hope this helps.