I regularly see or hear people say that they're no good or painting, or that they'll never be able to improve. That, to me, is a pretty silly attitude. With practice, anyone can get better. To help prove my point, here is the first model I ever painted (about 3 years ago):
And here's some of my latest Marine stuff:
Without trying to self-aggrandize, I think that's a decent improvement.
How did I get there? Well, besides practicing, there's a number of great resources at your disposal. Check out other hobby related blogs, forums, etc. Lots of people out there have made fantastic guides and tutorials totally free of charge. Of course many places like CMON, and even GW, have painting books and DVDs for sale.
Of course the number one thing is to JUST DO IT. Paint models, paint models, paint models! After that, the hard (but vital) part is to seek out feedback on them. And you should not be afraid to receive and give honest, critical feedback. Empty platitudes that so many hobby forums specialize in do no one any good. Hell, many forums explicitly forbid criticism! So seek out those places and people that will be honest and helpful. You'll be all the better for it.
I'm off for vacation for a week, but when I get back keep an eye out for more painting and hobby related articles, including details of the upcoming painting challenge at Gamers Sanctuary!