If you're using GIMP then I reccomend visiting gimptalk.com. There you can find numerous tutorials and plug-ins for GIMP. Also if you cant seem to find brushes or fonts that you like try dafont.com and devianArt. There you can find numerous fonts and brushes to add to your current GIMP selections.
o_O? Already trying for animated sigs and avy!? Well then I reccomend that you read up on some tutorials cuz animations can get tricky depending on how much you want to do.