Weathering Techniques?

Hi folks,
I am new to the world of painting and weathering of HO locomotives or any other models for that matter. I was wondering if any one out in the forum world could recommend any books on the subject of “Weathering” techniques. I am creating a fleet of about 39 mid 60’s to modern day era locomotives, no steam just diesel. I purchased last fall a nice little Badger airbrush which I will try out when the rain stops coming down (late spring, California). Have purchased many locomotives off ebay with road names that will be stripped off and repainted with new decals and weathering, if I can learn how before I ruin anything. Allot of practice I am sure.

Thanks,
Brad

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