One Piece of Advice

Water leaks kill RV's. If you are able get on the roof and look at all the seams. If there are a bunch of untreated cracks you could have a problem. Next look inside at the roof for water stains. Look in the corners even inside the cabinets. And finally check the floor carefully for stains or signs of leaks. In any suspect spots push down with your thumb or the tip if a screwdriver and see if it's soft. Cracked caulking on the roof is a $10 tube of Dicor. If you find any soft spots it's your choice whether or not to buy. But personally I would run.

Awesome advice so far, keep it coming! The central themes I'm seeing up to now:

• Don't rush into a buying decision
• Do all the research and think about your specific needs, lifestyle requirements, and brands.
• Consider a rent-before-buying option
• Get a walkthrough and inspection

Insist on getting from the seller - whether new or used - a complete walkthrough, inspection, and demonstration of EVERYTHING in the RV. This should include everything: water heater, refrigerator, microwave, toilet, tongue jack, stabilizers, furnace, AC, control panel, awning, water pump, winterizing, filling and emptying tanks, flushing tanks, etc, Ask questions and Ensure that you understand how every system works and that every system is working.

This means yes, you want them to demonstrate to you by actually put water in the tanks, flushing the toilet, running water in the sinks, and then draining the water in the tanks, You actually want them to demonstrate turning on the refrigerator and verify it works. Same with furnace, AC, electrical, electric cord, batteries, pump, etc.You will learn a whole lot about how these systems work and at the same you will know that they work as intended; or they will fix them before you pay them. This should take a couple of hours but is time well spent.

It would even not be unreasonable to pay a couple hundred dollars for this “service”, but I would negotiate hard for it to be included without extra cost; depending on how good the “deal” is to begin with. It would be money well spent for a first time RVer in my opinion.

All great advice so far!  I'd like to add that you must be ready to troubleshoot and repair the many systems and construction of your RV.  They all need repairs whether a $10K older used rig or a $500K new bus, so be ready to become a carpenter, plumber, and electrician.  The appliances, furnaces, A/C units, water pumps, electrical distribution systems, etc. are all from just a few manufacturers so problems seem to pop up on all makes and models of RV. 

don't rush it.  We all want that shiny new rv as soon as we see it, but take your time, figure out exactly what kind of camping you like to do (this may change as you get older also) how much space do you need and so on.  Use RV forums to ask people that have ones your interested in as to what they think of them..  don't ask the person that just bought one, ask some one who has owned the same model for a few years, usually we are over our purchase honey moon by then ;)

what type of rv do you want, truck camper, trailer, 5th wheel, maybe motorhome.  largely this will be a factor of the type of camping you like to do.  if you like getting to those remote places with some 4x4 roads, then a truck camper might be the way to go, if you do a lot of long trips (as in distance drove) a 5th wheel is the nicest to tow, but it need a better truck as more weight is on the truck its self.  if you drive to a location and have full hookups and just stay there for a couple months then something with lots of storage might be what you want, a big 5th wheel or a motorhome.  

think about the layout.  spend an hour inside the rv on the lot just sitting and moving around to see if it works, visualize your self and the kids (if you have them) trapped inside the rv for a couple days because of some bad weather or what ever and decide if there is enough room for everyone not to be tripping over each other and the functionality.  ie. can some one be cooking while the kids are playing and not bumping into each other? 

then when you know what you like for a floor plan, look at different brands with similar floor plans and really pay attention to the little things.  look at the fit and finish, are the cabinets wood or veneer core, or pressed fiber board.  are the cabinet frames hardwood or thermal foil.  what are the counter tops made of and are they the same in the bathroom as they are in the kitchen.  plumbing is a big one, are they using braded flexible hoses with pex crimps (this is not proper but so many do it.  it just means you will have to keep an eye on it for leaks down the road) 

better yet when you find that one that seems to check all the boxes, if your not the kind of person that knows a ton about he mechanical and electrical systems, considering spending the cost to hire a mobile rv tech for an hour or two, it might be money in the bank as they will know what to look at that we don't.  what they find might not be a big deal, but you will know what could cause issues or what might not down the line.  

First time buyers - you don't know what you don't know, and as a result you will probably not buy your last RV first. The moral of the story is that you can research 8 ways from Sunday to find your perfect first RV but until you actually start RVing it's almost impossible to find "the one". Every RV has concessions.  Because we are all different - advice should be heard but tested to meet your needs. The best advice I can give if you are buying, research brands (it matters), walk through as many RVs as possible - spending LOTS of time in ones you think will work and visualize life in it. Imagine making dinner, how much food storage you need, how comfortable is the sofa, the seats, the bed. What's the noise levels like, during the day, driving, at night? How is life with the slides in? Can you access everything you need? So much more considerations to buying an RV than a house. If you think you have "the one", try and find one to rent before you buy.