My reply is nearly word for word the same as Clares!
I use the 3M cutting compound with a mop, followed by one or two coats of a high resin polish (I use Autoglym).
The mop isn't essential (cutting compound can be applied by hand) it's just considerably easier and less tiring if you do use it.
As Clare said, go easy if you do use a mop - it needs to be kept as flat as possibly to the bodywork, and do not allow too much heat to build up in the pad - ignore these two golden rules and you will ruin your car in less time than it took to read this sentence.
I have also heard good things about the clay bar (a lot of the ferrari dudes use it) as it picks off microscopic bits of crap off of your paintwork, that washing misses, meaning it is 100% clean and debris free before you begin the polishing operation.
Alternatively, check out ebay - there are a number of guys operating on there that do a full days valet using real high end products (including clay bar) for about £200. They are there the whole day and will travel to wherever you are. Your car will never look as good as it would with one of these guys.
http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&category=72201&item=7966040766&rd=1I may have the Zymol one done (they come up on ebay from time to time) in the summer.