If you take your time and read many of the posts by prospective used RV buyers and all the sage advice given in replies, you will be ahead of the game. On any used MH, here are the basics in my opinion. Don't bother with a MH that has any evidence of water damage inside, very expensive to fix. Tires older than 5 years old per date code, are a blowout waiting to happen and should be replaced with name brand RV tires of the proper load range. Tires go bad just sitting parked in the sun and weather regardless of appearance. Brake fluid must be flushed and changed every couple of years and entire brake system serviced/repaired including replacemnt of front flex lines for your safety. Then engine cooling system must be checked/serviced and all belts and hoses replaced as needed. All appliances, water pump, water heater, furnace, roof A/C and dash A/C and must operate properly in all modes. The RV generator must start easily and power the roof A/C and microwave. Make sure that the converter charger is working properly on "shore power" and generator power, and that house batteries are good condition. ( 12 volt electrical systems and battery maintenance are very important).
Buy a popular brand rig whose company is, and will stay, in business. Buy a rig that has a rear bedroom with RV queen size bed about 27 feet long. Don't be over-awed by length. Slides are nice but source of problems. Appliances and roof A/C etc may die after about 10 years
Keep some cash in an account to pay for it when it happens. Learn how house batteries and converter charger work together, monitor battery voltage and maintain electrolyte levels and clean connections.