On my recent trip to Georgia, I got to hang out with some friends as I noted below. During my time there I got to see (and borrow!) The Imperial Armor Masterclass book from Forge World. First off, this book is awesome. Totally awesome! Its is a must read for anyone painting tanks, particularly Imperial Guard tanks. Additionally it reviews techniques that I have been exploring with oil based paints, other thinners, and weathering pigments. Thankfully, I was able to barrow the book- but now I think I'll need to purchase my one copy. Its that good.
I then grabbed a sponge from a blister back and added Foundation Paint Charadon Granite and applied it randomly to the tank to represent paint peeling- thus starting the weathering procedures. Be sure to focus on areas that will suffer weathering/paint peeling the most- around the edges, near crew access points, around moving turret parts, etc.