Remove doors and drawers.
Take off all cabinet hardware including hinges. Label and place in bags.
Set-up paint station for drawers and doors.
Tape drawers so that you are only painting the wood part, but not the whole drawer.
Lightly scuff already painted cabinets with extra fine sandpaper or green Scotch Brite pad. Pay extra attention to any previous brush marks and imperfections. Fix those with sandpaper before beginning.
Wipe down cabinets and all surfaces to be painted with a deglosser.
Make sure cabinets are completely clean and dust-free.
Trim out areas on cabinets with a brush that the small foam roller will not be able to get. You want to work in stages.
Once you have trimmed a few areas or ridges in the doors, use a small foam roller to paint all flat areas with high-quality paint like Sherwin Williams Emerald Urethane Trim Enamel. Working in thin layers will be your best bet.
Let the first coat dry and repeat the painting process for at least 2 coats of paint.
Look at your cabinet from multiple angles to make sure you are painting all areas evenly.
Let the paint cure for as long as you can (at least a few days).
Put hinges back on and put doors and drawers back in.