My secondhand RV has already cost me $4,600 in repairs. Here are the 12 mistakes I wish I'd avoided.

• I bought a used RV with no research and limited investigation, and it's cost me $4,600 in repairs.
• I wish I knew several things before buying, like how to make sure everything really works.
• It also takes a long time to get inspection appointments, and RV repairs are very expensive.

A few years ago, my boyfriend and I decided to buy a used RV a week before going to Burning Man - and we did just about everything wrong.

By not doing our research or checking the RV out properly, we ended up with a total lemon.

When we got to the festival in the desert, we discovered that almost nothing worked. We had no air-conditioning, fridge, or shower, and the water pipe leaked. We also had two tire blowouts, got towed, and had to get our battery jumped multiple times.

Needless to say, we've lived to regret our naive decision-making process.

Since then, we've started doing some much-needed repairs on our own. But they've already cost us $4,600, and they aren't close to done yet.

Here are 12 things I wish I knew before we funneled all of our money into our used RV:

Don't purchase an RV without doing the proper research, or you will pay

Now, it seems silly to even have to say you shouldn't buy an RV right before going on a major trip. But then again, that's exactly what we did.

We didn't know anything about RVs, and we certainly didn't do the proper research. We ended up paying dearly for that in the form of a ruined trip and expensive repairs.

There are a lot of great and easily accessible resources online, from RV forums to Facebook groups to YouTube videos.

Before you even start looking into specific models, take some time to learn about RVs and the lifestyle in general.

If we'd done this, we would've discovered that the reality of owning an RV doesn't always match up with the picture-perfect shots that we saw on social media.

Have the sellers go around and prove that everything works

We were in a rush, so we didn't make sure everything worked before buying.

We took the seller's word that the shower worked and that it just took a long time for the AC to get cold when in fact, the shower didn't work and the AC never got cold.

We ended up replacing both ourselves ($100 for the shower and $450 for the AC).

The sellers claimed they lost the key to the spare-tire cover, but they assured us that the tire was in pristine condition. We didn't discover the huge gash in the spare until we needed it after our first blowout on the way to Burning Man.

The tire was an unusual size that we couldn't find on such short notice, so we had to get the RV towed ($500 for a flatbed trailer) and pay a premium ($1,200) to quickly replace four out of the six wheels.

We also didn't run the water in the sink or bathroom before signing the deal.

Had we done so, we might have discovered right away that the gray water pipe leaked. But instead, we didn't notice until we were at Burning Man, and we ended up having to leave the event early because of that.

Make sure to look up the actual ages of the tires

Don't be fooled by tires that look OK. Ask how many miles they've been driven and check the actual age - the four-digit code right after the DOT label on the sidewalls is the week and year the tire was made.

As a general rule of thumb, RV tires should be replaced after five years.

Had we checked the date, we would've realized that the tires were more than 10 years old. Instead, we discovered that the hard way by having two blowouts in two days.

Not only did we put our lives in danger, but since we had a schedule to keep, we ended up paying top dollar to replace four wheels on short notice.

Test out everything, and make sure the living spaces fit your needs

Try out everything as you would use it on the road because you won't know if something is big enough or comfortable enough otherwise.

My boyfriend is 6-foot-2, and he didn't fit in the shower but we didn't know that until it was too late.

The bed is also too small for him and because of the RV's layout, we can't magically come up with more space for it.

Look for water damage and mold all around the RV

Used RVs almost always have some water damage. Luckily for us, ours was fairly minimal and obvious.

We got lots of sealant and thoroughly taped, sprayed, and caulked the roof, windows, edges, seals, and vents ourselves.

When looking for water damage, make sure to do so beyond just the roof.

Check to see if there are stains in the wallpaper or if the walls bulge. Look for soft spots that may be indicative of rot. Check around the windows and trim. Look for mold in the cabinets. And most importantly, get on the roof of the RV and check for tears and holes that could indicate a more serious water-damage problem.

Get your RV professionally inspected

It is critical to get a full inspection if you're purchasing a used RV, particularly if you buy it from a private party that has no real obligation to tell you what's wrong with the vehicle.

Inspections only cost a few hundred dollars, and they can save you so much more.

If that's not possible, at the very least, bring along a knowledgeable friend who can ask the right questions and know what to look for. Neither my boyfriend nor I knew anything about RVs, so we had no clue what the minor, or even major, problems were.

Had we gotten the RV inspected, we would've realized how many issues it had, and we wouldn't have bought it.

And make sure to budget enough time to set up an inspection appointment before your first trip

We knew we messed up by not getting the RV checked out before buying it, but we didn't realize it would take months to get an appointment.

In our case, it was right around Burning Man, which made the wait time even worse. But even under normal circumstances, it's not unusual to have to wait a month for an appointment.

When we finally got our RV in for a full inspection three months later, we were given a total estimated repair cost of $8,800.

RV appliances and repairs aren't cheap, so you should know what you're working with before buying

We quickly realized we had problems with the fridge. The estimated cost of labor plus materials to replace that was over $2,500.

We ended up removing the fridge and relying on coolers instead. If we wanted to buy a small one down the line, we'd be looking at $400 for even the tiniest mini-fridge.

Our onboard, ceiling-mounted AC unit also didn't work. To have it professionally replaced would have cost $1,600.

We decided not to replace the ceiling AC unit. Instead, we bought a room AC unit for $350 and installed it ourselves. We used the space where the fridge had been, framed it out to fit the room unit, and added insulation and vents.

Additionally, our onboard generator didn't work, and it was going to cost at least $3,000 to replace it. To save a little, we spent $500 on a 4,400-watt portable generator, to power a few items including the AC, and bought high-capacity power banks to run smaller items.

Be on the lookout for scammers when you're shopping around

We found our RV on Craigslist and thought we were prepared for the worst, but we were no match for the charm of the seller's three kids, who reminisced fondly about the many recent family trips they took in the RV.

My boyfriend and I got so caught up imagining the picture-perfect RV lifestyle that when their father "forgot" to bring the title, we didn't see it as the major red flag that it was.

By the time we got the title, we were literally completing the sale - and getting ready to leave for Burning Man the next day.

Had we investigated, we would've realized that the RV hadn't been registered for the past four years, which calls into question all those family road-trip stories.

Thoroughly investigate the history of your RV

This is another critical step that should be done before purchasing a used RV.

Unfortunately, we didn't run a DMV check or CARFAX report until after we returned from our disastrous trip to Burning Man.

When we finally did, we discovered the lack of registration, several questionable sales, and inconsistent odometer readings - which are all huge red flags that would've stopped us from buying that RV in the first place.

You have to factor in the cost and effort of RV parking and storage, as well

You may think, like we did, that you can just park your RV where you live. But it turns out our homeowner's association, like many HOAs, doesn't allow it.

RVs also take up a lot of space, and you may not be able to protect them from the elements at your house.

If that's the case, you'll have to find and pay for a space to park your RV, which can be expensive (several hundred dollars a month), far from where you live, and difficult to access.

This is all information you're going to want to know before you sign a deal on an RV. All those costs add up, and you might not be able to spend as much up front as you initially thought.

There will be a lot of ongoing maintenance costs, but never skip out on the important ones

It costs a lot to maintain an RV, which you need to do to prevent even bigger issues down the line.

Depending on where you live, you may need to winterize it when the weather gets colder. And if you don't, you just might have to replace your entire plumbing system, as a friend of ours had to do.

You also need to check things like seals, valves, brakes, and fluids on a regular basis, and every season, you also have to change your RV's oil filters and maintain your waste-water system.

Unless you're mechanically inclined, you'll need to take the RV in somewhere for regular servicing, which is going to cost you, but it's definitely not optional.

And all that doesn't even factor in the amount of gas you'll need once you're on the road. That's why it's so important to know what you're getting into before the initial purchase and to have a clear vision of what your budget needs to be after the fact.