First, take care of the most important item. No, not the radio. Saturday night's dinner. Statistics show that the average Field Day participant's ratio of eating to operating time is approximately 10:1. Everybody gathers out at the Field Day site and works hard all day stringing up antennas and putting up tents. But most of them want to spend the rest of the day and evening eating and talking rather than sitting in front of a radio. So its important to prepare a good supper for Saturday night. That's what most of them are going to remember anyway. The LIDS prefer a good, hearty chili. With beans and meat. The beans are important. You need lots of them. LIDS chili is renown for recreating the campfire scene from "Blazing Saddles" in the 40m cw tent late at night. Newcomers run in teary eyed terror. You can find chili recipes everywhere, so we won't bore you with ours. But just a word to the wise. The key to a great chili is adding a little peanut butter and chocolate. Trust us.
Sometime during the weekend, somebody will likely suggest that you make a few radio contacts. Remember that Field Day is not a contest, according to the ARRL. You keep score and they report the results ranked by score, but this IS NOT A CONTEST. Say it enough times and we'll all believe it.
If this is your first time on HF, you'll notice all the signals aren't "full quieting". This is normal. There is no courtesy beep. Just key the microphone and start talking. Preferably when the station you're trying to work has stopped talking. When he calls you, don't worry about being ready to copy his exchange. He'll be happy to repeat it again for you. If you do copy his exchange the first time, make sure you repeat it back to him and thank him for it. Then ask him to "please copy my..." and give him your exchange. Follow these hints and nobody will spot you as a noob.
If you decide to wander down to the cw bands, be aware that sending "PSE CPY..." is perfectly acceptable.
The last bit of wisdom we wish to impart is a bit of planning advice. Setting up for Field Day is a lot of fun. Operating Field Day is a lot of fun. Taking down for Field Day is the least fun thing you can do all weekend long. Show up early and leave before the party ends, or else you'll be stuck cleaning out the chili pot on Sunday.