gratuities?

[Mr. 16 gauge]

So, not to look like an "ugly American", what is considered a fair gratuity for a safari of 7-8 days, and who all needs to be tipped? I'm assuming that the trackers, skinners, ect., but what about cook staff, wait staff, launderers, ect? Drivers?
Last hunt I went on, I had 4 "guides"....by the time I got done with tips, I was flat busted!