One question @mons , what is the best resolution for sending original images? Sometimes I think the resolution is good, but it turns out not to be.
By the way, I can't upload photos from Instagram, can I?

It's not the image size which is important but how large the face is within it. It's useless if it's a full-body shot in 500x500, when compared to a full-face 200x200 image, which is easier to cut and can produce a better cut.

You can't link directly from Instagram, but you can use an app like this to get the image in question and upload it accordingly.

Got it. Thanks for the tip. I see some photos on Instagram and don't know how to send them.

You can copy the instagram post link from the share option, and use a site like this one to download the photos