Make sure the dates are centered (sometimes they'll be right or left justified). Make sure the bezel lines up with the indices, make sure the SEL (on the bracelet) look good, make sure nothing is crooked like any of the applied indices, and make sure theres no major blemishes or marks on the bezel and dial.
I mean you can get really complicated with this, but if you check these five things you'll be in good shape. Also keep in mine you're staring at a magnified picture on a computer screen, you'll mostly never see any of this stuff in person on your wrist, but the stuff i mentioned is a good start. Hope that helps!