Haha it takes some practice I guess :P Good luck with the CSSing though - my knowledge of it's pretty basic (hence why I do everything in GIMP first) or I'd help.
Yeah, if you're shrinking a large-ish gif to avatar-size it does drop the quality a bit, so I usually just find gifs that already kinda small to crop. I think ImageMagic + coalesce is the best option for resizing, iirc.