I am making sprites for my Dragonball Z clone of Liero, and have encountered some problems.

I do not want to use a 3d modeler...because I dont need that....this is a 2d game....a 3d modeler is way too much to use for this....

I have tried hand drawing my sprites in paintbrush....but that makes them look childish and not very well done.

Are there any good sprite making programs out there? I need a program that would aid me in making my sprites. Especially when my sprites for characters have to be as small as 13x13 pixels....