To increase the chances of having Google pick the cover photo you selected, make sure you do the following:
Pick an image that looks good in both landscape and a square layout
Pick an image that has most of the image in the top half (not the bottom half)
The image should be a close-up and not have a ton of background detail
An exterior image is generally preferable to the algorithm
Use the dimensions 1332 x 750 for the cover photo
Use this trick from Ben Fisher to get Google to display the correct photo
