How much should I tip a personal photo guide?

I have a personal dive master / photo guide that has been helping me find some really great super-macro subjects. How much should I tip him? Does it depend on the country or does that matter? (I live in a very low wage country) I want to make sure I take good care of him! Thanks in advance, Larry

The single most important thing about deciding how much to tip is what country you're in. In Australia where I live, an appropriate amount is $0.