good advice from BSmatic...keep the idea and animation simple at first,a few frames and small changes in animation,then try to make them fluid and smooth with small increments in motion and experiment with variation in timing (speed of transitions) till it feels right.Your gif in the tennis ball comp is a good effort a little complicated to do properly imo for a beginner,but the idea is very good.Here was my first gif,two frames,as you can see very simple but effective .My second one also two frames:
as you can see I didnīt know how to do the hat movement properly so I made it as a still image.Later after learning a bit I fixed it to this:
Keep at it and you will improve quickly...
Thanks Luxwiz. You first GIF is effective. But I really liked the idea behind the second one. Thanks for advising.