Practice is key. I am sure you can find hundreds or thousands of good tutorials online, and you can and should look at them, but the #1 way to get better is to just practice and experiment with tools. I taught myself how to use PSP 7, and I can do things on that that many skilled people cannot do with Photoshop (and I never used a tutorial. It takes me more time, but I can create nearly photo realistic images with PSP7 that many people struggle to do with Photoshop, despite the fact that I have a vastly more limited tool set.)
Practice, practice, practice.