Preparation accounts for most of the success when repainting cabinets. Your kitchen is a high-traffic area; the cabinets are exposed to several handprints, grease, cooking splatter and other issues.
Before you do anything, remove the hardware from your cabinets and the doors. When you remove a door, mark it with a pencil on an inconspicuous spot you won't paint over so you can place the cabinet doors on the correct cabinets. If you have cabinets with a clear coat finish, stripping may be your best bet. Clear coat finishes are very hard and durable but may cause issues with paint adhesion.
If you want to skip stripping, which is time consuming and sometimes difficult, you'll just need to clean thoroughly and sand the surfaces. Tape off every surface near the cabinets you don't want painted, including walls, ceilings, countertops and backsplashes. Set up sawhorses or other work areas that will hold your cabinet doors off the floor for easier painting.
Using a roller cover isn't often recommended for cabinets because they leave stipple marks in many cases. If you're painting the entire cabinet and not just the outer frame and doors, take note that getting in tight spaces such as the inner corners of your cabinet is difficult with a roller; you'll need to use a brush inside. If you have smooth cabinets, you can often use a mini-roller or foam roller to roll them. When you begin rolling, apply thin coats as opposed to thick coats. Don't attempt to roll cabinets that don't have an almost perfectly smooth surface, and always choose a roller with a very fine nap.
Besides spraying, brushing leaves the smoothest finish when done correctly. When you brush cabinets, always use a high-quality paintbrush. As with rolling, two or more thin coats leave a better finish than one thick coat. Brushes also get into corners more easily than rollers. While you may about brush marks, know that -- especially with latex paints -- the brush marks will level out as the paint dries. Whether brushing or rolling, let each side of the door dry for several hours before painting the other side.
For kitchen cabinets, a semi- or high-gloss finish works best. The glossier the finish, the easier the cabinets are to clean. Several latex paints are manufactured specifically for kitchens and are durable and cleanable. Spraying the cabinets provides the smoothest finish; you can attempt this yourself or hire the job out. Latex paints take up to three weeks to cure, much longer than alkyd paints take.