One Piece of Advice

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.