The only tip I can give is to compress it to 75x75 by your own means.
Not to mention, but that's a terrible avatar. It'll be compressed terribly, it's already a .jpeg and you won't be able to read the text.
Why not get something else that can be seen? And try to keep it as close to 75x75.
I'd imagine Square avatars also work best.
Edit: I've compressed it to 75x47 for you, which is the same aspect ratio. It's also a .png now, to stop reduction of quality again.