While specifics vary, the guide should help you locate fish and catch them. The guide should accomplish this while keeping you as safe as possible. Other than that there are a number of things you and the guide need to understand to make your trip a success. Services do vary.
-- How much time are you buying and at what cost? Customarily trips are a half or full day, but you want to be sure you know how long that actually will be.
-- Where are you meeting and when? Will transportation be provided?
-- Do you need a license; if so, find out where you can get one and do it BEFORE YOU MEET!
-- Will water, soda, snacks and lunch be provided? Any food allergies?
-- Will equipment be provided? If so what? Rods, flies, etc. Is your own gear appropriate?
-- What casting skills are required? Be honest in assessing your own skills. Tell the guide.
-- Will this trip, like most, be all catch and release?
How you can screw it up
-- Forget to tell the guide your food, insect, allergies, special medical concerns like diabetes, hemophilia, mobility, circulatory and respiratory problems. Inability to swim.
-- Neglect to mention you weigh 450 lbs...because you're the small one in the party.
-- Assume it's perfectly fine to drink as much alcohol as you want on the trip. On our boats, it's no alcohol and no barbs on hooks.
-- Show up late at the meeting place, without your gear and license.
-- Bring an unexpected companion...even if it barks.
-- Dress inappropriately for the conditions that MAY come up. This includes serious sun protection, polarized sunglasses, good rain gear, insulation when you need it. Shorts are rarely a good idea; flip flops never are.
-- Loudly correct any of your loved boat partner's perceived imperfections.
One More Tip
What's the deal on tipping? Customarily it's like a waiter -- 10 to 20%. Most guides will knock themselves out for you. Sometimes you wind up using an inordinate amount of the guide's flies, leaders, etc. It's appreciated if there's some recognition of that when the tip is being calculated. Typically, the guide will work harder and try all the tricks when you're not catching fish. This is the time to really watch and learn. It's bad form to blame him or her if the problem lies with you or nature's conditions.