Totally subjective, so check out some of the cars that have their's done. I personally prefer it without tint. So, my suggestion is none or very lightly done on a white car.
Get what you like, tho.
'13 Individual Frozen Brilliant White ///M3 Coupe
Ordered 2/15/12 | Euro Delivery on 9/21/12 | U.S. Redelivery on 12/6/12 | Motor Dead on 7/15/13
'13 Space Gray/Mugello Red X5///M
Pavement Punisher | Snow Muncher | Family and Board Hauler | Roadtripper