I fish with the same guide on the same lake at least twice every year. I tip each trip based on how hard he worked that particular trip, not just on how many fish we caught.

I would ask the guide beforehand about maps and gps. Tell the guide what your expectations are and see how he/she reacts. Most guides are more than willing to teach you techniques and strategies. As someone else mentioned, specific locations will vary by season and year. However, general locations (rock walls, mud banks, creek channels, etc) are fairly predictable. Just try to be friendly and you will pick up a lot of good info.