I really don’t get it how people can continue pirating proprietary software like some Adobe products (Photoshop, Illustrator, etc.) when there are quality, Free Software alternatives like the Gimp or Inkscape.
Sure, Gimp currently lacks some features you need for professional printing like CMYK, but that doesn’t disqualify for the use in non- or semi-professional environments, at home. You can even use Photoshop brushes in Gimp, so you won’t miss those. Good resources for Photoshop brushes are Qbrushes and DeviantArt.
Working with the Gimp might be a little different, many complain about the interface but it’s not as bad a people say once, you got used to it and start using hot-keys. Try using <TAB> in one of the newer releases, and you won’t have to complain about multiple windows anymore. In most of Linux’ window managers you can set any window to stay in front, all the time which is another method to get those windows not to float around behind the main window when you need it. If you’re using windows, just get DM2 to get the same functionality. It’s a little app, that doesn’t even need installation.
To get started you should take a look at those numerous tutorials for Gimp available on the Internet. You can ask google for some, but those I found most helpful were gimp-tutorials.net and gimp-tutorials.com.