Step 8: Finishing touches
Add a background and maybe a few special effects, and you're done! It may seem unimportant, but a background can add a lot to how a picture looks. A character in some sort of setting looks considerably more professional than the character standing in a white void, and even just a solid color with some simple patterns can make the artwork look a lot neater. Adapt the background to complement your character(s).
A parting reminder: details are important! Your work suffers if you get lazy and gloss over things. I myself have been guilty of this. ^^; The difference between pictures that make you go "not bad" and "WOW *_*" are often entirely in details. You don't have to rework every pixel when the detail is too small to be noticed, but taking the time to highlight individual strands of hair or folds of clothing goes a long way. Effort shows.
Finally, don't be afraid to experiment! If you think you can do something better than what I described, or if your graphics program has a different way of doing things, TRY IT!