Remove the door or doors of your cabinet with the screwdriver. Set the hardware aside and clean off old paint, if necessary. Set the door aside and plan to paint it last.
Put on work clothes, gloves and glasses if you have not already. You may want to cover your hair and use a disposable mask as well, if sensitive to paint fumes. Painting a cabinet may not be a large job but requires you to put your face close to the project to see what you are doing from various angles.
Wipe down all cabinet surfaces with a damp rag or sponge and mild soap. Pantries accumulate an assortment of sticky or greasy spots, even if they are hard to see. Rinse and let surfaces dry thoroughly.
Sand all surfaces lightly, to improve paint adherence. Wipe off sanding residue with a damp sponge and let the cabinet dry thoroughly.
Begin painting by covering the back interior wall and then the side interior walls of the cabinet. Use either your 2-inch brush or mini-roller for this part of the job, depending on the size of the cabinet.
Paint the ceiling and then the undersides of all the shelves. Some painters prefer to work top-down, others bottom-up.
Paint the floor of the cabinet and the upper sides of all the shelves. Again, do this top-down or bottom-up.
Let the inside of the cupboard dry at least 12 hours -- preferably overnight. If you are painting in humid weather or your kitchen tends to be damp, allow 24 to 48 hours' drying time.
Lightly sand, then paint the cabinet door, inside and out. Let it dry thoroughly, up to 24 hours. If it is part of your decor scheme, paint the front cabinet facing to which you will attach the door.
Clean the door hardware of old paint or other imperfections or replace it with new hardware. Attach the door to the cabinet.