Remove all the hardware, doors and drawer fronts. Use a degreaser or teaspoon to clean grime and dirt. Sand just enough to get the glossy surface off. A palm sander or a mouse sander (we use a multi-tool for corners, will save hours of hand sanding. While sanding will produce the best bond, you can skip sanding by using a deglosser product in areas that cannot be sanded. If needed, repair deep scratches with wood filler. Wipe any dust off before painting.
Setup your painting area. If you can't remove the drawer fronts, you can prop them up to dry. Doors should ideally be lifted off the floor for drying. Wood blocks or plastic cups work well to prop them up.
Coat with Appropriate Primer. One coat provides enough coverage for brushing/rolling. Use 2 light coats if spraying or if drastically changing the color. Allow to dry 24 hours. If any stains come through, recoat those areas.
Paint the cabinet doors with 2 coats of cabinet paint. See notes about using a sprayer.
Allow to dry. I generally allow the doors to dry about a week before flipping over to prime and painting the front sides.
Paint the frames. You can paint the cabinet frames while waiting for the doors to dry. You can either tarp and spray the cabinet frames (pictured) or paint using a brush and roller. Generally, there is no need to paint the insides except for glass fronted cabinets.
Add a protective clear top coat. This is optional but highly recommended for most paints to make cleaning easier and the paint will last longer.
Put the doors and drawers back on. Full cure can take up to a month, so I suggest leaving the doors and drawers ajar for at least a few weeks.