My advice - never stop! Draw, draw, draw. Photograph things, turn them into textures, jot down ideas you have, test new things in Photoshop or your package of choice. Read on-line tutorials, start building up a gallery of screen shots from games where you really admire the graphics, or if you see a film poster, or CD cover you love the design of, keep a copy of it somewhere. Have a look at some traditional drawing / painting technique books, they'll teach you loads about the use of shading, light and colour. You can get stacks from your local library. The same goes for books on photography, general design, and typography. Never stop reading.
If you really want to be the best you can be, then keep on at it, day after day - I do honestly believe that with graphics there is required a basic artistic ability, which some people have, and others do not. But the rest of it is pure technique, and you can teach yourself this over time.
Trust me - it's NOTHING to do with the software you use, an experienced artist could outdraw a 'Photoshop using noob' with a copy Microsoft Paint any day.
Heavy on the Magick