I worked at a popular hotel chain for 3 years. Here are 10 common mistakes I saw guests make.

• I worked at a popular hotel chain for three years, and I saw plenty of guests make travel mistakes.
• Forgetting your credit card or ID makes check-in difficult, as does using someone else's card.

Until recently, I worked at a hotel chain that was always busy — during peak tourist season, we were sold out most nights.

Having such a large number of guests all the time meant I witnessed countless people make the same mistakes over and over.

Here's what to avoid so you can save money on your next hotel stay and ensure everything goes according to plan.

Booking hotel rooms through third-party websites

If you've had a good experience booking third-party, congrats, you're very lucky. But I've had countless people call me (sometimes crying) desperately trying to get the money they spent on a booking website back.

Although the customer-service department for the site told the person we could help them, we usually couldn't. They were the ones who had their money, not us. How are we supposed to refund money we haven't even received?

Often, these websites will even sell rooms that the hotel doesn't actually have available, fail to communicate your accessibility requirements to the hotel, or book you in for the wrong date. That's just a short list of ways things can go wrong.

If you want to guarantee you'll have somewhere to stay during your trip, I strongly recommend booking directly through the hotel by visiting its website or calling its phone number. Some hotels even price-match third-party sites and have way more flexible cancellation policies.

Paying extra for a free cancellation policy

If you book third-party and purchase the fully refundable option, I applaud you for having enough foresight to realize that things can (and often do) go wrong. But these policies can tack on as much as an extra $50 to the cost of your room.

Many people don't realize that most hotels have super flexible 24-hour or same-day cancellation policies for no additional cost.

I cannot stress this enough: Book directly through the hotel.

Not joining loyalty programs

If you travel a lot, I recommend choosing a hotel parent company and signing up for its loyalty program.

Companies like Marriott, Hilton, Choice Hotels, and IHG have thousands of hotels worldwide that you can earn points to redeem for free hotel rooms and gift cards at popular retailers.

Our hotel staff was also encouraged to treat loyalty members like VIPs, which means you could receive perks like discounted rates, free suite upgrades, or free early check-ins/late checkouts.

Forgetting to open up your Bible — hear me out

If your hotel room has a Bible in it, there's a chance the last person to read it may have left some money in there.

I think the intention with this is probably to share the wealth with other Christians, so I'm not going to tell you to take that money if you don't feel like it was meant for you. Just know that this is a common practice.

Do with that information as you wish.

Trying to use someone else's credit card

Hotels only allow you to use someone else's credit card if the card owner has provided the hotel with a credit-card-authorization form.

Without authorization, the card owner could easily file a charge-back request with their bank, and if the bank discovers the reservation was under a different name than the card owner's, they're going to take that money back from the hotel.

"But I've done it at so many other hotels!" I've heard it time and time again. But believe me, whoever allowed you to do that would be in trouble if management found out.

Not reading the documentation at check-in

It's just good practice, in general, to read things before you sign them. Reading the documentation you're required to sign at check-in will help you understand everything you're agreeing to and avoid confusion when checking your bank statement.

Even if you don't feel like reading it, the front-desk agent will most likely summarize it for you, explaining all the important things you need to know.

I highly suggest listening to this spiel. Most people don't and then make it the staff's problem when they're confused about something.

Complaining about your room at the last second

Dirty room? TV not working? Loud guests above you? You don't have to endure these inconveniences for your whole stay — bring them up ASAP.

The hotel staff can almost always fix whatever issue you're having. You might even get a free suite upgrade for your troubles.

Showing up without a credit card or ID

The vast majority of hotels don't accept debit or cash and require a credit card on file so the staff can access your funds in case you damage the room.

Even if you used your card to book the room online or over the phone, we couldn't let guests check in without swiping the physical card.

You'd think providing government-issued ID would be a no-brainer — obviously, the front-desk staff isn't going to give you John Smith's room if you can't prove you're John Smith. But apparently, a lot of people don't realize this.

And no, a student card or picture of your ID on your phone isn't usually going to work.

Not knowing the difference between a charge and an authorization

Tale as old as time — a guest checks their bank statement and sees that they were "charged" significantly more than they were supposed to be, then calls the hotel and makes it their problem that they don't understand how credit cards work.

Most hotels don't charge you until you check out. This means staff has to pre-authorize your credit card when you check in to ensure you'll have enough money to pay for the room at the end of your stay.

They also have to pre-authorize a certain amount of money as an incidental hold in case you damage the room. Don't fight them on this — it's standard practice, and you will not win.

These authorizations look the same as the charges on your statement, but fear not, they should be reversed within three to five business days after checking out.

I've had many guests tell me they've never had a hotel do this to them. I can assure you they have, and if you don't think they have, it's simply because the authorization was reversed quickly enough for you not to notice.

Forgetting to check out

Technically isn't a mistake, but it's a common misconception that the checkout process is pointless.

It doesn't need to take long — even if you just shout to a staff member on your way out that you're leaving, they'll appreciate it.

It lets them know you're gone so the front-desk agent can complete the technical checkout process and housekeeping can start cleaning your room.