The first two has been talked to death in all modeling books so I'm just going to run through.
Drybrushing can be done with most paints, but I prefer enamels or oil over acrylics. Lacquer dries way too fast...
Drybrushing can ruin your brush so take an old one. You can slightly burn the end of the brush with a lighter to make it more "dry". I bought brush specially used for drybrushing which has very hard bristles, but they're not really worth the $.
First take some paint on the brush and wipe most of it away. The paint should be a lighter color of the base coat.
|Here's the gun holding hand of Misato. I base coated her gun with gun metal and is dry brushing steel on it. Lightly sweep the brush on the raised areas and the paint will deposit on them, accentuating the details. You can do this in stages, lightening the color every time, as well as softening your touch so you get a nice gradation of highlights. I tend to drybrush oil once, and then blend a little bit to achieve the same effect.|
|A wash is just some very thinned paint. Usually the color is a darker version of your base coat. You can do a global wash which means you take a brush and deposit this thinned paint all over the surface. Or it can be controlled, which means you only deposit it around areas you want. The thinned paint will deposit in crevices. Here I'm doing a global wash with Misato's hair using a matte oil of ultramarine blue mixed with some black. I'm trying to kill the shine in the hair grooves.|
Now if you take a paper towel and wipe the wash off the raised area of the kit, I think that's called glazing (?). I wait for the oil to dry a bit before doing this, so that the paint that's in crevices are very resistant to your wiping action and will stay there. By doing glazing I don't usually need to do drybrushing.
I also use local wash combined with glazing to do panel lines.