Whichever country you travel to, you always need to be careful of your belongings in crowded public areas, and Bangkok is no different. A good idea is to carry your backpack in front of you, or invest in a fanny pack that you can wear under clothes to avoid keeping your money in your pockets. If you're carrying a handbag, try and hold it in front of you. A common trick is for motorcyclists to grab bags as they ride by. If the bag is in front then it is harder to grab. Even if you're not carrying much on you, it's always best to stay alert in public areas just in case.