Heres a short pictorial on how to do rust. If at some point youre creating old looking pieces, doing rust is a must. I have a couple of ways to do rust. The long way consists of 11 different color combinations. I've refined it down to 4 colors, white glue and real fine sand. i'm sure there are alot of ways to do rust, heres my way.
Sepia, White Glue, Sand