Freddy
In looking over your posts above, I see that you have access to a farm and compressors, so you should be able to do this yourself. Not that a farm is needed, it just means you likely have the space you need to do this properly. Furthermore, it isn't necessary to bake the cabinet in an oven or even sit it in front of heat lamps as long as you use an enamel with a hardener added to it. These are often referred to as catalyzed enamels, and the catalyst, or hardener if you will, ensures that the paint hardens all the way through.
To reduce the risk of runs and sags you'll also want to use a descent spray gun capable of producing an even spray pattern. Make sure that the hose you connect to this spray gun hasn't been used with an oiler for air tools at any time, as oil in the paint will ruin it. In fact, if you have any doubts about the history of the hose you'll be using, buy another one. They aren't all that expensive so why take chances.
Make sure you have a water trap at both ends of the hose. A large one on the tank side will catch most of it, a smaller one at the spray gun hose fitting should get the rest.
A pressure regulator at the gun is also helpful, as pressure drop though the hose is always an issue. The longer the hose, the greater the drop, especially with smaller diameter hoses. All of the spray guns I've ever used have a minimum required pressure at the gun to ensure proper atomization of the paint. So set your tank regulator above what you need, and then use the regulator at the gun to make your final adjustments.
Spend more time prepping the surface of your cabinet before you start painting. Very often the difference between a great job and a poor job is found in the prep. Feather out your chips and scratches and use primer surfacers where needed. You want your surface to be smooth and defect free prior to applying any paint.
You'll want to buy a bit more paint than you'll need so that you can practice on something unimportant before you actually paint your cabinet. Painting can be a bit tricky until you figure things out. If you apply it too dry(meaning not enough paint applied at once), it won't flow out properly and your finish will be rough and textured like an orange peel, a condition that's even referred to as 'orange peel'. Apply it too wet and you'll end up with runs and sags. When spraying your practice piece, pay attention to what the paint surface looked like just before a run or sag formed. Then you'll be able to avoid them better when you spray your cabinet. If you do end up with a small run or sag, don't panic. Let the paint dry thoroughly and then you can glue some fine wet sand paper to a small flat block. You can then use this block, along with water, to sand the top off the defect until it's the same height as the surrounding paint. Then polish it out to bring the shine back.
In spite of what others have done, I would personally not paint over porcelain enamel unless it was badly scared and chipped up. Scars, like chips and deep scratches, can be touched up rather effectively with paint as long as you have a really good color match. It requires patience though, as you'll need to build up several layers of paint, letting each one dry in turn until you've built it up above the level of the surrounding porcelain. Then using a small flat sanding block as described above, sand the touch up paint back down to the the level of the porcelain. By applying plastic tape to the surface of the sand paper at both ends of your block, you can get enough height at the center to keep the paper from sanding the porcelain. Then as mentioned above, use a polishing compound to bring the shine back. Done properly your touch up will be difficult for most people to spot.
Painting isn't easy, but it's a worthwhile skill to have. Nevertheless, after reading all of this, you may very well decide to have a body shop do the painting for you. If you're only planing to paint one cabinet it may even be cheaper for you. But if you think you're going to be painting multiple cabinets(or cars) in the future, the investment you make in equipment now and the time you spend learning, can save you money in the long run.
