Whether to join a lot of the discount RV Clubs or not depends on how you plan to travel. If you are going to be moving around a lot, then Passport America would be a good one to join. You get 50% off member parks although there are some restrictions on a park by park basis. Some limit the number of days, some exclude weekends or holidays. It is up to the park. But at 50% off we made back our annual fee in the first week.
Good Sam Club gives 10% off at a lot of locations so you can usually get your annual fee back. If you buy fuel at Flying J you can also use the card for fuel discount and propane discount.
Escapees Club has park discounts from 15-50% but not as many parks take it. They do have a few of their own parks with large discount for members staying there and they have many other benefits for membership you could check out at their website.
There are a lot of parks that give discounts for military, AARP, AAA, or things like that. Sometimes you just have to ask or look for a sign at the office. Many times if you are staying for a week or a month, they will have a discounted rate for the longer term that will be cheaper than any of the club discounts will get you.
HTH, and welcome to the forum!
Vicki