Finding an avatar is the easiest thing for me to do. I tend to just use the same one on all the forums I'm part of. Sometimes I'll change my Discord avatar to the one I use on forums, but I hardly get on Discord. Mine are usually based around Sonic or Raven from Teen Titans most of the time. The only time I have an issue getting a new one is when the avatar file size or dimensions are weird like on phpBB forums out of the box.
I used to have a hard time finding an avatar until I decided to just use my own picture. If I want to switch things up, I’ll get ahold of a few of my graphic designer friends to create me something, which is rare in itself. Obviously finding an avatar can be difficult depending on your own tastes.