Sometimes is not the best but the one you can do.
As I told you before there are a lot of techniques, I supposed that if you are asking, it’s because don't know much about that, pigments, oils...etc.
The best technique I know is the hairdryer one, but honestly I think is very much for what we are talking here ( Miguel Jimenez MIG made a terrific Dragon 1/16 with 4 layers chipped)

So back to the beginning, I strongly recommend to begin with simple techniques, if you are looking for a little difficult one, then the salt is a choice.
http://www.modelersite.com/en/481/a-...que-using-salt

The chipped paint using brushes has been useful for years but nowadays there are new techniques with better advance results, but as I commented before, they are more useful for advance modelers and / or 1/35 scale.

By the other hand, remember that WWII American didn’t have chipped paint, but scratches and other kind of marks. The tanks were painted without base paint and cured to high temperature ( like the powdering we know today)
Good luck!