Bring A Padlock
Make sure you only book a hostel that comes with lockers. They don’t tend to come with locks on though, and to ensure your belongings are protected as you explore the city you should bring a padlock.
It won’t take up much room in your bag and can be the difference between coming home with your belongings or not. The best type of padlock to buy is those with number combinations, that way you won’t have to worry about losing the key while you’re out being an adventurer.
If you’re traveling with a friend, then make sure to split your valuable belongings between you. Maybe take it in turns to hold on to your passports so that one person isn’t burdened with making sure you can all go back home. Bags with extra compartments are perfect for putting passports in because they can take longer to rifle through for a thief, which means they’ll target someone else.
Under Your Pillow
During the night, make sure to sleep with your phone either under your pillow or in a pocket on your body. This is particularly important when you’re staying in a room with lots of people. You should also make sure you padlock your bag at night and keep all of your clothes inside.
In general, staying in a hostel is safe, but being extra careful will prevent someone from stealing your stuff and ruining your trip.