I bet you've tried it already (or you've seen it happen): you wander into an art forum, and announce you would like to learn how to draw. The first advice you usually get is “draw a lot”, or “practice practice practice”. And this is exactly what you should be doing. Your drawing skills won't improve just by reading about it.
However, drawing the same mistake over and over again is not the most efficient way to improve your skills. The first part of the tutorial will show you some of the basic principles, and hopefully will help you to practice in a more focused way.
For now, we'll stick with realism. Don't let this discourage you if your favorite style isn't realistic, though! Unless you're an abstract artist, the basis of your favorite style is the world around you. So let's tackle that first, it's difficult enough already without adding all sorts of stylistic conventions.