I will echo the comment about a backpack. If doing much travel - especially if hopping around a bit, travel as light as possible and do not do it with a suitcase. Also, keep your valuables on your person. I will sleep with my passport and wallet either in my pockets or inside of the pillowcase under my head - if someone's trying to take stuff from there, I'll probably notice. Also, I'll keep anything else valuable (i.e. camera, computer, etc.) either in a locker or (if they dont have one) snuggled up with me in the bed. A cannon is not a teddybear, but I've found you can get used to sleeping with one pretty well when you don't want it stolen. As most people in hostels are all traveling around just like you with similar things, they probably are not all that interested in picking up some of your stuff to take along with them. That said, it's always better to not let temptation present itself.