The most important thing to remember is this - Guides are people too. Each has his/her own personality and quirks, just like you and I. Even if all your pictures indicate that they may be in the witness protection program!
Guides can often be the key to the success of your fly fishing adventure. It is important that you get along and work well together; communication is very important. When you first meet your guide let them know how much general fishing experience you have, how much experience you have with the specific type of fishing you will be doing together, whether you cast right or left handed, what you want to get out of your fishing days, etc. Spend time getting to know each other - friends fish better together than strangers do!