Like the title says, I'm offering to try to share tips, critiques and editing assistance with book covers on Tapas. I'm also hoping other people chime in but I'll do what I can. I'm not an expert but I've been an comic artist here on Tapas for a while and I've got at least a little graphic design experience.
So to start these are some resources provided by Tapas themselves giving some basic pointers, tips and other useful information on how to produce a good cover for comics/novels:
https://tapas.io/newsfeed/106
https://tapas.io/newsfeed/107
For folks who may be looking to see how other folks have put together their covers consider browsing this thread if you like:
If anyone knows of a thread for novel covers let me know or we can make one
Lastly there's a handful of resources folks often point to for 100% free to use images as well as image editing tools which you can find here:
https://www.canva.com/
https://www.pexels.com/