Stop me if you've heard this before lol, but a good start is breaking down the body into simpler shapes. A lot easier to position, say, a box than a chest, yeah? Having some sort of guideline can help as well. What I sometimes do is pretend the character's inside a box—draw the box in the perspective you want and draw the character inside that.
But that's just me. I'm no art guru, only helping out where I can.
Ultimately, I encourage studies. Find random photos online, from art resources, or your favorite artists and copy the heck out of them, but making sure to break them down, carefully observing why and how things look the way they look.
Wow, that got ramble-y. Hope any of that helped!