For weathering it will depend on your ultimate goal. If you plan on just being deployed i.e. police officer, your armor has to have a dirty appearance - no specific patterns have to be made.
If you go for SWAT, the weathering will have to match what's onscreen for the specific trooper you're recreating. The screen captures linked above would be a good starting place.
There are some specific recommendations for the cantina captain in this SWAT app:
http://forum.mepd.net/index.php?showtopic=12890
Good luck.