+1 to above warnings. RV's are complex vehicles and will break and require maintenance. Remember it is a vehicle first. Any used vehicle should have all new rubber parts installed. That means all belts, hoses, tires if over six years old. I also change all fluids front to back including brake, transmission, power steering, oil, anti freeze, and rear end. Do these things and you will eliminate the causes of most highway breakdowns. Nothing is worse than a motorhome that will not run.
Then make sure you understand exactly how to operate every inside appliance and feature. Most do not require a lot of maintenance but some do. If you are in a cold area, learn how to winterize or know where and when to have it done. Do not neglect maintenance! I have owned every type of RV from a pop up to a large class "A". We full timed for three years in a class "A". Much of what I have written here comes from hard experience both as an RV owner and former professional mechanic.