make the anim smooth by adding in lots of frames

Trace over key frames so there are basically two of each, have inbetween frames play for a slightly shorter amount of time than the key frames, and make sure to have the animation move fairly quickly. (FA's fastest preset speed, for example.) This anim -> took 6 frames to be individually drawn, then I copied the two inbetween frames in reverse to make it loop. That's my advice at east. :p