Wall Texture Recommendations?

After years and years of using a myriad of bought terrain, my group is finally taking the plunge and making our own from foamcore. Our first one has turned out pretty good so far, but there's one thing I'm not sure on - how to get texture on the walls.

I've seen a ton of different ideas on the internet - mixing fine sand with paint, stucco, thin plaster, spackle, and textured paints. Some of the best I've seen used textured paints, but others with textured paints don't look so hot, so I'm not sure what's the best option. This forum has some of the best pieces I've seen so I definitely wanted to see what people here used.

For the experienced terrain-makers, what is your favorite way to make texture on the walls of ruins? If you have particular brand recommendations, that'd be appreciated, but any ideas would be welcome.

I have used paint, glue and sand on foamcore before, varying the sand to glue ratio to achieve different degrees of texture.  This method is very easy, but I think other methods are much nicer looking. Be careful with this method though if you apply the glue to just one side of the foam as it can cause the foamcore to warp when the glue dries.

Another method when using foamcore is to peel off the paper in layers to get a nice stucco texture.