You don't necessarily always have to make graphics by drawing them pixel-by-pixel. If you're good at image editing, you could always just take pre-designed art (from a scanned sketch, photo, clip art, whatever), do whatever editing needs done (cutting things out, resizing, etc..), and convert the colors in PCE format. You could even take photos of your dog and edit them to be used in game! (Infact, HCF has already done so!)
But practicing pixel art is best, as Gogan posted. If you're making sprites that are in the 16x16 - 32x32 range, you're probably better off drawing by hand anyways. Lord_cack started making tiles with no experience and after a couple years he became an incredible artist.