The generally accepted "best tool" for pixel work is Cosmigo's pro motion. If you don't feel like paying $80 for your pixeling tool, Graphics Gale free edition works nicely, as does the GIMP. Other tools, tutorials, etc. can be found in
this thread.
To reiterate what was said in some other thread, a newbie "here's a collection of helpful info so we don't get several hundred 'I'm a n00b' threads" could be quite handy.