"How do you eat an elephant?"
"One bite at a time!"
I'm sorry for the corny advice, but I find it's very, very true in art. Pick one thing -- this can be a fundamental like line, shading, gesture, etc., OR it can be a particular piece of anatomy like the shoulders, knees, hands, stomach, etc. -- and work on that for a week, see if you notice an improvement. When you can't figure out how to do something, look it up! Youtube, books, drawing friends, etc. are all great resources. Then lather, rinse, repeat. Address whatever bugs you most about your art, which should change as you improve.
I also found I started improving a lot faster once I started using class mode. The longest drawing should always be pushing you to do a little more than you're comfortable with.