My wife and I and 2.4 kids all have private plates so I must have changed about a dozen set of plates over the last few years.
I've always asked the dealer not to screw them as I can't stand drilled plates. Anyway not one has fallen off and I've just used the cheap rolls of double sided from ebay.
Like dubber has said, its all in the preparation. I usually clean the area then use tardis and some G101.
I don't even use that much tape, a bit in each corner and a strip down the middle.