I don't think you can predetermine a tip amount before going on a hunt. There are just too many variables to consider without knowing the details of the particular hunt that you booked.
I've been on over 25 guided hunts and have had pretty much the full gamut of guides. I've had guides who were so loud mouthed, obnoxious and full of themselves who couldn't guide you to an animal if you were surrounded by them. I've also had guides who were almost therapeutic to hunt with and were so good at what they did that it almost seemed uncanny their ability to put you on animals. The obnoxious guy was the only one who I've ever stiffed and the therapeutic guy I tipped 20% several times and felt like it wasn't enough.
It's really a subjective thing. How hard does the guy work for you? Do you get along? Is he just the guide? Or is he a guide/cook/wrangler/packer/etc? The amount of work that a "guide" will do varies a lot from outfitter to outfitter. If your outfitter is also your guide, that can come into play as well.
Generally speaking though, if you are between 10% and 20%, you won't be far off.