- Keep practicing. The most obvious advice, but will also return the best results if you stay motivated enough to follow.

- Explore a lot of different styles. I like comparing things like graphic novels, web-comics, animation, etc., and seeing how they differ.

- Explore resources. You can get Youtube tutorials for just about anything these days.

- Don't be afraid to "cheat". This might not be a problem for anyone else, but it was for me. I used to look down on certain techniques like using tracing and photoshopping to create a piece of art because it "wasn't made from scratch" and "didn't reflect the natural skill of the artist". But I soon realized that it's all about the end result, regardless of how it's made.

- Seek feedback. You can spend hours scouring over and analyzing your own work, but there are always things that only some fresh eyes will see. Even if the person isn't a particularly arty person. - If you're using graphite pencils, ALWAYS keep them sharpened and learn the differences between the grading.

- Practice drawing lines. Seriously one of the best exercises. Like warming up before you play a sport, I like to warm up before I draw. Sometimes I practice drawing straight lines while playing with different pressures. This helps me to draw more confident lines.

- If you're trying to draw things realistically, getting your proportions correct are quite important. I used to suck at drawing faces, but once I learned how to scale and position everything properly, they started to look more like real faces and less like aliens. For example, the eyes are usually positioned in the middle of the head, but for some reason people tend to draw them a little higher. Same goes for hands, a lot of people seem to make them a little too small (although hands are notoriously difficult to get right).

That's about all I can think of right now. If you post some of your stuff, I could give you a little feedback if you like.