Like Black Sheep said, expand your horizons.
For chipping I use and enamel silver for the undercoat and then AK Interactive's "Worn Effects. This is similar to the hair spray method but designed specifically for chipping. An acrylic (XF-???) goes over this, then you can wash the acrylic off where you want or chip it off with and X-acto blade.
For rust I use oils. Either Burnt Siena of Burnt Umber. Mix just a tad with Turpenoid and apply with a small brush, the oil does the rest.
For mud I will use chalks and pastels. Wet the surface with water and apply the pastels to the wetted area. The pastels won't come off and they will clump up like mud.
Steve
Even I took a stab at answering one of his postings ,but I believe you and Blacksheep are talking a little over his head, just judging from his queries.NO OFFENSE.