For years I bemoaned that I couldn't draw very well, and so I didn't draw. In January 2000 I got over it and realized if I didn't draw, I certainly wouldn't get good, but if I did start drawing, at least I would probably improve and might get good. I decided to draw something every day, even if it was just a small sketch. So far I've stuck with it, and it's very enjoyable. A handy exercise is to flip through a magazine with lots of photos of people and draw them. (Adbusters magazine has lots of fun odd pictures to draw.)
A common problem when drawing is that your brain recognizes what you're drawing and summons up iconic preconceptions like "This is a face, which is a circle with 2 little circles for eyes." A handy technique to overcome this is to view the source picture upside-down. Then your automatic recognition gets suppressed, and you can focus on seeing the lines & curves that are actually there. I got this technique from the book Drawing on the Right Side of the Brain by Betty Edwards, which I recommend as a very interesting & useful book. She talks about the dominant verbal logical left brain needing to be shut off, and letting the spatial intuitive right brain take over.
I started out with pen & paper drawings, but also did some digital painting and then got into online comic strips at The Bench.