Priority to crop: male, futa, slime, fay, taur, mermaids.
I try to primaily download pictures with simple backgrounds and full body standing characters. But, i can get carried away and download everything i consider suitable. So, if you think that cropping will take lot of time feel free to skip picture.
Upd. If you meet pictures with same character: take the best looking one, two with biggest&lesser boobs, two with clothed&nude version,
Here are some tips: To find hidden white pixels at the edges, use a black background fill on a new layer. To find missing transparent pixels, use a magic selection on empty pixel, without anti-aliasing and contiguous, you can combine it with a subsequent fill. To avoid working on the same image, leave in the comments the folder you started working on, sort the images by name and work from the beginning of the list, I will do from the end. If you think that the picture is too complicated for processing, put it in a separate folder called "for later", if , do not overwrite the original, save the result in a new folder with the name "job done", transfer the original processed image to the "ready" folder. I'll deal with the rest.