A money belt is either a real Belt which you can store banknotes in, or a silken/cotton belt which you wear under your clothes.
I can just suggest you to get one of both to keep your money safe when travelling. Mostly Pickpockets are really fast and quiet so it will be hard for you to notice you've been stolen from. It's even worse if you notice it, in the moment you want to buy something or someone asks you for your ID.
Lastly, if bad things happen and you get mugged, it's unlikely that they steal your cloth and/or look underneath them.
Depending on your sleeping-place, you can also consider to wear the money belt while sleeping. It might be a good idea to do that, in order to not get robbed.
Your backpack is without doubt the most valuable thing on your journey (except your health). You should never leave the eyes off it, as long as it's not safely locked somewhere.
You will find yourself in different situations where this might happen, here some examples:
Let's say you're sharing a TukTuk with two friends. Obviously there is no place
anymore for three huge backpacks, so the driver suggests you three to take one TukTuk
and put the baggage on another one. I'm not saying all TukTuk drivers are crooks, but your baggage is most likely gone!
A similar situation. You're taking a TukTuk alone, or sharing it with a friend.
The TukTuk is full, you're sitting on the edge. PUT YOUR LEG THROUGH THE STRAPS OF YOUR BACKPACK!
It's possible, that someone will try to grab your backpack from a motorcycle in a impressive drive-by. Don't let them succeed!
Again, you're sitting in a vehicle, a cab. The diver suggests you to put the baggage
into the trunk. I'm not saying this happens often, but doing so you have no control
what happens to your backpack. It's an easy act for the driver to have a companion to
take it out of the trunk in at the next lights. Of course it will be a "thief",
the chance the driver and him a friends is pretty big though.