I've painted a few kegerators amongst other things, and if you are going with a single black color look for appliance epoxy at your local hardware store. I think rustoleum makes one. They take a while to set up and harden, but they are very chip resistant and have a consistent sheenand come in spray cans. One stage auto enamels are nice if you have spray equipment. Stay away from laquers as they dont play nice with the cheaper enamel finishes on some appliances. If you want that glass smooth look, you are going to spend some time with autobody filler and a plane, then go with a 2 stage auto enamel or urethane. The latter is tons of work, but comes out beautiful...be careful though, if the sheetmetal on your freezer is thin or the insulation behind it isnt good and hard you will have issues with paint cracking/separation if you go the autobody route.
I did one once with the appliance paint, changed from green to white. I cleaned it very well and scuffed it up with a scotchbright pad, masked it off and spray painted it. It came out looking as good as new.
I painted mine with Rust-Oleum Hammered Black paint. This hides any imperfections when painting. I decided against spray paint as I wanted to do this inside. I went with the quart size can and a foam roller. Total cost was $13.00. I am VERY pleased with it.
I washed it with some oxi-clean, and then scuffed it with some 180grit. Then I wiped it down with a damp rag to remove any sanding dust/residue. I then taped off whatever needed to be taped off, then proceeded to paint. If you do this in your house OPEN THE WINDOWS!! This sh#t stinks!
With the flash on my camera it looks a little green. Let me assure you it is not.
At Walmart they sell rustolium in a qt can in many different colors and you can brush/roll it on. It works really well and its really tough. Here is a pic of mine painted in black. I liked it because it gave me better control so I didn't end up with over spray.