Please, please, please don't paint it black. No matter how nice you do it it will not look as good as body color. I think the body color engine bays are the reason Mopars look so much nicer uner the hood than GM products.
That being said, if you do decide to paint it black, first spray a ton of degreaser on the engine bay and pressure wash it. Next let it dry thouroughly. Then, sand it down with 320. Next, blow of all of your dust and hit it with some wax & grease remover. Prime any spots where you sanded through to metal. Left the primer dry and scuff it. Lastly, spray you paint. If you are going black, you can use a spray bomb it you'd like. I personally like Duplicolor Engine Enamel. It sprays smooth, lays down nicely, and can withstand higher temperatures.
