Editing avatars

[Cammotion]

How do you edit an avatar so that it will be accepted for use. I have some that are small in pixels, and around 30-60K, but are more than 1,000 bytes. I see some of your avatars appear large, and was wondering what programs you use to do the editing. Thanks,

Bill

[DareBee]

I use this online tool http://www.gifworks.com/
or MS paint