Before you ask for help, put yourself in the place of the appraiser or authenticator and logically ask yourself what you think they might want. Clearly if it is a mask, good images of the front, back, sides, and maybe closeups of any areas of interest would be helpful. Or maybe its a rug. Shoot a good general shot and maybe do some closeups of the design and then include a shot of the back around a corner. Maybe it has fringe, or areas that are torn or stained.. All of this would be good to know. Collection history, any previous appraisals, exhibition history, invoices are actually helpful in the physical examinations. Some information that appears insignificant may give us a clue of something to look for in the examination. For example if I see that another appraiser valued it high but the documentation said it had entered the U.S. in the last ten years, even if it looked stylistically OK, I would be far more suspicious as I examined it. So if it helps make a checklist before you send off your information; it may save you some money.
Wireless phone companies advertise that many of their cell phones now take images in excess of 10 megs. The size of the image does not ensure that image is good. Look at the image before you send it. If it is blurry or dark, or upside down, don't send it. The appraiser just may accept them... then you will really have a problem.