I want to get better at graphic designing to create wallpapers for smartphones and tablets, so that I can release them for free at a download manager soon. I use GIMP and PhotoShop, however, I only use PS for image re-sizing, cropping, and the simple image editing tasks.
Does anyone have any advice that I can use so that I can start creating amazing wallpapers? Are there any resource websites that I can find useful images to include in the wallpaper? Of course, I can't just Google an image to use since it might be copyrighted, because I am releasing them for free on the Internet.