We’ve all had that “oh no” moment when it dawns on us that we forgot some critical items for a trip. When traveling internationally there is an extra-long list of must-have items you might not use in your day-to-day life. It’s easy to accidentally forget something or not even realize you needed something until you're halfway across the world.

Deciding on what kind of bag to take on your trip is important because size, shape and type of bag matter. When choosing travelers need to know if their bag will be checked or carry-on only. When traveling, I choose not to check my bag, which means whatever bag I choose needs to be within the standard carry on dimensions; the biggest allowed is 9 inches by 14 inches by 22 inches (22cm x 35cm x 56cm).

If during your travels you plan on walking long distances or anticipate standing for long periods of time, then a rolling suitcase might not be the best choice. Instead of having to lug around a rolling suitcase around there are many backpack options that are easier to carry with you, no matter the terrain.

For my trip to Europe I am using a backpack with straps that can be tucked away and effectively converted into a handheld suitcase. It’s the exact dimensions of the maximum size carry-on with hip straps and shoulder straps. REI has a big stock of these, or if you’re like me and you’re traveling on a budget, Outdoor Regear in Albuquerque is a more reasonable option.

Countries around the world use a variety of different electrical socket models and it’s important to know what kind of adaptor you will need for your trip.

In the U.S. the standard electrical output is 110 to 120 volts. In Europe the standard electrical voltage is 220. However, most phones and laptops are now dual voltage. For appliances like hair dryers or medically necessary machines, such as a CPAP machine or nebulizer, a converter is needed.

Additionally, travelers will need the appropriate adaptor to charge devices. Visit the International Electrical Commission World Plugs page to find which adaptors you will need for your trip. Travelers can also buy a world set of adaptors online or at Lieber's Luggage in Albuquerque.

If travelers are planning on venturing outside of the country for longer than a month and are on any prescription medications it is important to request a vacation refill several weeks before departing. Travel refills allow travelers to fill their prescriptions before insurance would ordinarily pay for it, and to request a larger quantity of the medication than normal.

When staying at hostels during a trip there are multiple items travelers should pack that they would not need elsewhere. First, many hostels do not provide guests with towels for free. Traveling with a normal size towel would be inconvenient. Instead, a microfiber towel will dry within minutes of use and take up hardly any room at all.

Some travelers may opt to pack a sleeping bag if they plan on staying at hostels during their travels. If this option seems like it will take up too much room, then packing a sleeping bag liner is a wise choice. They assure that regardless of the quality of linens, you are clean.

Many travelers find themselves concerned about being pickpocketed or losing important documents such as their passport. Travelers who are concerned about this should purchase a passport wallet. They hang off your neck and are a secure place to keep passports, IDs, and credit or debit cards.

As likely as not, travelers don’t plan on carrying all of their luggage on person at all times. For this reason, it is important to pack a smaller bag such as a backpack or purse. I would recommend taking a bag that can be easily moved to the front of your body on public transportation, to prevent being pickpocketed or having the contents of your bag smashed against other things.

For this trip, I decided on a backpack, but as an extra precaution I attached safety pins to the zippers to prevent theft. During my travels I will keep my passport, laptop and forms of money on my person.

A few days before departing on your trip, travelers should plan on printing out any documents from airlines and hostels. These include travel documents, flight receipts, hostel confirmations or anything else sent to your email after purchase. If travelers have prescription medication, printing off a list of prescribed medications is a good idea too.

Travelers should make two color copies of their passport. The first color copy should remain with the traveler’s emergency contact in the home country for the entire trip. The second color copy should be brought with the traveler, but kept in a different place than the actual passport.

This is so if a traveler’s passport is lost or stolen, the color copy can be taken to the nearest U.S. Embassy. During this kind of an emergency the embassy will see that the color copy provided matches the color copy back in the United States.

Megan Holmen is a freelance news and culture reporter at the Daily Lobo. She can be contacted at news@dailylobo.com, culture@dailylobo.com or on Twitter @megan_holmen.