The problem with black, is that it shows up micro-marring or swirls quite easily. If you car has this problem, then before polishing I advise using a good swirl remover. Meguiars No. 9 2.0 is probably the best one to apply by hand using a cotton applicator sponge. Or 3M Swirl Mark Remover is also good, but a little harder to use. Both can be got from www.autodetail.com.
Once the swirls are gone give the car a good wash to remove any oils left behind; which interfere with the bonding process of the polish you will add later.
As for the polish, I recommend Autoglym SuperResin. It's not that expensive, lasts ages, and is on par with some of the more exotic stuff from the U.S. Some people prefer the Teflon polish I see, but seeing as Dupont, who are the inventors of Teflon, say it offers no added protection due to needing a temp. of 400 degrees to bond, I wouldn't bother with this. Anyway, check out www.autoglym.co.uk.
They have a free guide on how to use all their products, and it's very useful.
The super resin stuff by the way, will clean you paint, remove light scratches, and give it a nice shine. So it's an all in one cleaner and polish. You will want to follow up with some Autoglym extra gloss protection. This will seal that shine in and it contains some waxes as well, so will give your car a glossier look. And if you would like to add some depth to your paint, then you could top it off with a good caranuba wax. I recommend Blitz wax. Available in the UK from www.frost.co.uk.
Other good waxes are P21S Concours, Pinnacle, and Zymol, all available from autodetail. I'd stay away from Turtle Scratch though.