GIMP is a powerful, feature-laden, and expandable piece of software, and there's far too many add-ons, extras, and tips to cover in a single, quick overview. The best way to really develop your proficiency and skill with it is to read up on more tutorials, tips, and tricks on websites like the tutorials repository in the official GIMP site, Gimped!, and Gimpology. Surf the web, ask around in forums, and get your hands dirty with a lot of first-hand action. You'll get the hang of GIMP in no time!
Do you have any favorite GIMP tips and tricks? Particular tutorials that you found really helpful? Clever plugins, filters and extensions that you've found indispensable while working with the software? Feel free to share them with your fellow readers in the comments section below!