take some life-drawing classes
Only 374 days to go until I can do one without my parents permission!
But again, like the others said, it takes time and practice, and crap loads of study...my suggestion, start with simple geometrics and apply different forms of principles (balance, texture, rhythm, etc, arty terms) to it, then try mixing them, then do the same to other objects until you've mastered that crap, then start doing...well, the stuff you need to make. :-/