First and foremost, find something you really want to do. There are many different opportunities, ranging from RV Parks, to Amusment Parks.
My wife and I are finishing up at Adventureland Land in Iowa. Prior to this we have done: General Stores in Yellowstone, Animal Refuge in New Mexico, RV Park in St. Louis and we haven't even scratched the surface of the fun and adventure waiting.
I do recommend you get in writing what the job entails, expectations, wages (if any), number of hours and most of all, what is the length of the commitment. We had a bad experience with a park in the Northeast. Lasted one week. Another experience in the Northwest, which I take the blame, as I failed to get a full understanding of the job.
We enjoy it. Our goal is to try something different each year.

There are a number of resources available, we use the Workampers Magazine. As mentioned by Fulltimer, if you belong to any camping clubs, they too hire workampers.
Enjoy and have fun.
Bob