Is it better to resize an image before converting it from png to jpg, or to convert it before resizing it?
Same for cropping instead of resizing (but I guess that cropping before or after makes no diff)
Resize prior to any lossy compression - this gets you the best quality result for the intended pixel dimensions.
Lossy compression like
.jpg save space by calculating relationships and change of pixel arrays, so for best effect, you want to do all resizing in the base non-compressed image, and you'll get better results from the placing of the compressed image if the compression "knows" the final pixel size.