For the perfect thumbnail image and gig content images, the Fiverr gig guidelines recommend a size of between 1280 x 769 pixels with a minimum of 712 x 430 pixels and a maximum of 4000 x 2416 pixels at 72 DPI.
I've been here for a week and a half. It makes me feel good. I'm hoping for a positive experience. I'm expecting to get the first order as soon as possible.