Hi, we're also going to the Constantinos the Great this year on all-inc.
We've been all-inc about 7 times now, twice in Paphos. What we usually do is generally chat to the waiters/waitresses, and after the first couple of days of noting who gives the best service quietly give them a tip and if we get great service from them, another tip at the end of the holiday.
Sometimes if we drink after hours, get them a drink as well as our own, one girl a couple of years ago used to sunbathe on the beach in the daytime, so I'd make a point of taking her a drink.