Not sure what the application is...but Dupli-color make a nice Satin black trip paint. Works great for bumper mouldings, window mouldings and all the like.
Its like any other paint, a clean surface will go a long way.
A lot of care is needed when applying satin paint. The surface has to be prepared extremely well, and it has to be put down with very even strokes. Any flaws will be easily seen, and you really can't wet-sand them out.
Another vote for Dupli-color Black Trim Paint. I've found it's very temperature dependent. I forget what the can says, but only use it between 65 and 80F. As someone else mentioned, you can't wet sand out mistakes (well, you can, but buffing satin doesn't work).
The best method I've found for satin is after the surface is prepped (500 grit is sufficient), go for 4 coats of paint. Make the first 2 coats REALLY light and dry, then make the last 2 coats moderate, but by no means heavy. With satin, dry is better then wet, b/c satin doesn't really "orange peel". Allow the paint to tac over between coats (so that you can lightly run your finger across it without making a mark). Come back the next day and inspect it. If there are flaws in it, scuff the entire part with a scuff pad, wetsand out the flaws, and give it one final coat.