Picture quality/resolution

Hi! I’m sending my client a file for her to print at cvs. What’s the highest level of resolution and image quality to send it so she can upload it?
The highest quality is too big of a file to send and upload.
I want to make sure the quality stays good.

for printing i’d say min 300dpi and max 600dpi.
if its an illustrator file and you made a pdf, if you uncheck ‘preserve illustrator editing capabilities’ it greatly reduces file size.
also flattening files into single layers e.g. photoshop… helps reduce size.