The suggested picture size is 1280 x 769 pixels.
712 x 430 pixels minimum
Maximum 4000 by 2416 pixels
Additionally, leave some room on each side of the image.
If you are consistently receiving orders, you should seriously consider shifting your gig. If there are no orders, you should change your gig and concentrate on making something special.
No problem you can change your gig at anytime but do not change more time. after delete the gigs then create a new gigs and obviously focus on your gig images title description it will be help you to rank your gig.