Hi Eddie, I have to support everything that Eric has said. As a guide, I always enjoy taking people out who want to learn. Just remember that it is fishing, not necessarily catching. If the fish don't want to play, the guide will work his heart out anyway but he can't make the fish bite! It is more frustrating to him than it is for you. Based on on your post, make sure you communicate your expectations (learn a cast, relax, learn about trout lies, how to read water etc) sometimes you may not know what to ask so follow his guidance.
Also have your expectations aligned with and not exceeding your skill level and you will have a great day. One or two beer is OK with me, a six pack is not! There is a matter of safety that the guide will be concerned with, you know slippery rocks and such.... Tips are at your discretion, 15% of the guide fee is usual, more if you feel the day was better. A typical day drift on the Bow is about 6-8 hours, any "overtime" should be compensated and remember that the guide usuaully has at worked least 1 1/2 to 2 hours before and after the drift (making lunches, drive to pick up, drive home, set up gear etc). It is difficult for some guests to quantify this when it is their first guided experience, so use your better judgement and you should feel good about the tip.
Lastly, spend 75% of your time fishing, 25% practice/learning/correcting. Practice on the grass at home before you go and fish in the water while you are being guided.
Pete AKA Frenchcreek from Calgary