There are a few different techniques you could use. Small chips in the paint can be applied with a fine paint brush. To highlight the nuts, bolts, etc, a technique called drybrushing is probably your best bet.
Load an old brush with paint, then wipe it on a piece of cardboard until you see no more paint coming off of the brush, then brush the kit. It will eventually highlight the details if you keep repeating these steps. Be patient though, less is more with this technique, you can always add to it, but it's hard to take away.
Happy Modelling and God Bless
Robert