This may sound weird (depending on your age) but draw scantily clad people to learn how anatomy works. The more skin you see and the tighter the clothes, the more you'll learn how muscles flex, bend, and pivot around the skeleton. SI's swimsuit issue or pictures of male swimmers are good places to start. Not only are the people in those magazines close to naked but they're also very toned and/or ripped so you can see how musculature works.
Don't feel awkward about it; if you're going to learn how to do this correctly (and later go on to study it in college), nudity and the human body is something you're going to have to get comfortable with.
Other than that, keep practicing.
PS. to learn how to draw, do NOT study other drawings unless they're anatomy books (such as the great line of Burne Hogarth reference books). Learn how to realistically draw the human body and then interpret it into your cartoon/comic style as you please.
PPS. It is REALLY SHITTY to make fun of the OP. At least he's trying to learn a skill and create something with it. WTF are you doing with your days other than sitting on a fucking couch playing a goddamned video game that somebody else created? Cut the kid some slack, for crying out loud. At least he has the balls to get out there and try.
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