AS you search out these sites and read the information presented, it's still going to take the school of hard knocks to accomplish the finish you want.
I say "that you want" simply because we could give you all the info that we have collected and have been the result of our own experience and techniques and you would still have to practice (succeed and fail) and develop an eye and technique for what is pleasing to you.
Most impotantly you must realize your own abilities and match your expectations to meet those abilities. Do not allow your expectations to exceed your abilities or you will be in for disappointment. Some failure is good because we learn from it. We also have to be willing to fail in order to see what the boundries of our abilities are.
There are several techniques for weathering and getting the right amount is a subjective thing and often times the result of a happy accident. When is paint chipping too much? How much sun fade is there on a vehicle? who's to say what wasn't stored on the hull or upper decks of a vehicle? How much is too much? What is too little? (see what I mean?) You have to be the judge. What context are you putting your vehicle in? In a battle, patrol, enroute to position, pulled up for inspection, leisure, end of the day, begining of the day, in the woods, in the desert, on the beach, spring, summer, fall, winter, on the road, in the city, swamp, rocks, field, plowed field, after a rain, after being washed, maintenance? All these things develop context.
There is no magic bullet other than experience and what you are willing to try.
The websites that were referenced and the articles called out all are great starting points. Also learn to study a photograph. Look at the details of the vehicles pictured. What weathering do you see on them? Look at road vehicles and construction equipment around your area. see how they're weathered.
Good luck
Mike
"Imagination is the dye that colors our lives"
Marcus Aurellius
A good friend will come and bail you out of jail...but, a true friend will be sitting next to you saying, "Damn...that was fun!"