Hey! nice with another m113 I’m building one at the moment also
https://armorama.kitmaker.net/forums/203717&page=1 It wasn't long ago that I tried weathering for the first time so I can't say that I’m an expert but I find that weathering with actual paint is quite hard as the application tends to be quite heavy and it’s hard to get an even distribution. To avoid that you can apply it with an airbrush as Joel said so that you got better control.
What I prefer is to weather with pigments as I fell that it is easier and much less finally than actual paint. To dust your vehicle you just put some of it on and rubs it with a q-tip or a piece of paper to make it stick, the more you rub the more subtle the effect becomes. Also if things go South you can just remove the pigment with a wet towel and start over. To make mud you mix the pigment with some plaster and carefully put it on.
For pigments I use both products from MIG and AK-interactive but dry pastels works fine also you just grinds them to dust using some sandpaper.
That’s my opinion, happy modelling
Jakob