Debit cards and credit cards are not the same even though they may look alike. Debit cards are a direct link to a person's bank account and money is directly removed. When a debit card is used, it should be thought of as giving someone permission to remove money straight from a their checking or savings account.
Making Reservations
When making reservations, using a debit card is not a good choice especially if the reservation is being made in advance. Most hotels and airlines will remove the money directly from a person's account and hold it until the reservation time. With the money the card holders information is also stored and can be accessed by employees. This could allow access to a bank account without authorization.
Setting up Automatic Payments
Using a debit card to set up automatic payments is allowing someone to remove money directly from a checking or savings account. Once permission is given it can be stopped and changed, but it's easy to forget forget that the automatic payment was permitted. If a checking account is not updated and enough funds added to the account to cover these payments, this can cause an overdraft to the account. Overdraft fees are very expensive and can add up quickly.
Restaurants
When eating at restaurants, avoid giving a debit card to a waiter or waitress to pay for meals. The card is out of site when it is handed over and extra charges or tips could be added to the card. Even when the card is in site, charges can be added because they have the banking information.
ATM machines and gas stations
Charges at ATM machines and gas stations are high, and are always being increased. These transactions, as with automatic payments, get forgotten about and then the bank account becomes overdrawn. Another problem with using debit cards at gas stations is the risk of not knowing who the employees are that you are handing the debit card over to.
Online
Using a debit card online to make purchases is another way that unscrupulous people can gain access to a person's bank account. Once a debit card number has been given out, you are trusting that the business on the other end is a legitimate one. Even companies that are highly trusted such as utility companies are having issues with hackers breaking into their websites and business. Other sites that purchases are made from are usually small companies and records are not as safely kept private.
Although most companies are doing their best to protect the customers from theft, there are those that are determined to find a way to steal a person's money. It is the responsibility of the individual to try to maintain knowledge of when to use a debit card and when to use other means to pay. Sometimes it's better to be safe and wait on a purchase then to use a debit card and have some misuse it.

Comments
I guess cash is still the best way to make payment.
When it comes to ATM machines, the thing is to understand when you might be charged. In this country, at least, you don't get charged for using an ATM machine belonging to your own bank or other banks within the same network.
Same with my country. No extra charge if withdrawing from own bank but withdrawing from another bank's machine would incur a charge.
Thank you for sharing this important information.