@OP: It's not just practice. Yes, that's a large part of it, but you also need to simply be observant. Look at anything and everything in a new light, as if you were going to draw your life on paper. And every once in a while, you should draw some of your life on paper - once I just looked at my hand, noticed the cool lines in my palm, and decided to sketch it. Do stuff like this and you'll get better, regardless of whether you have natural artistic skills or not.