Here is the basic technique for dry brushing furniture as a color accent, but not necessarily covering the whole piece. Start with a fully stained, finished piece. If you are the one who has stained the piece, I would do the paint step before applying a clear coat.
I don’t dry brushing a piece that has a glossy finish at all. I would only do this on something with a flat or matte finish. You may need to sand to fix some spots and you don’t want to do that on a glossy surface.
(Note: Practice this on a board or some other piece of throw away wood before you start on the actual piece.) Dab your paint brush in the paint, maybe 1/4 of the way up the bristles. Then, using a throw away board, cardboard or a paper plate, paint back and forth until the brush starts to run out of paint and it is a real, dry “bristly” streak you are making with the paint brush. I would err on the side of having the brush too dry, when you start, than possibly not dry enough. It’s easy to add extra paint but harder to fix areas where there is too much paint.
Then, very lightly, just make small, short streaks with the brush over the piece, maybe 2-4 at a time before repeating the process with your paper plate or cardboard piece.