Check out detailing world forum for tips on what to use - they hardly use any of the mainstream stuff, and not all of it is super expensive either. Quite an interesting read. I use P21s paint cleanser, then Meguiars step 2 polish, then P21s wax. The P21s products are out of this world - they are way better than their Meguiars equivalents, although the Meguiars step 2 polish is about the best polish for the price (P21s don't do polish!) Matt.
If your using it on a Black car then SRP, followed with EGP then a really good wax or even Meg NXT Gen Wax. Dont be scared to mix and match to get the best results. Good place to check out is www.detailingworld.com so see what some products results are like and to get good advise.
I just bought my car (which is also black and a real b*tch to keep clean ) i used turtle wax colour magic which did wonders to hide the scratches but left it really streaky so I followed it up with autoglym deep shine and it came up beautiful buffed up with mucho expensive autoglym perfect polishing cloths and I'm very happy with the results BUT don't get it on the trim its left massive white marks that i'm having difficulty shifting
id have a look here tbh.... there are far better waxes and polishes available www.cleanyourcar.co.uk i would recomend Poorboys range for a cost effective outstanding finish... remember only polish if the car lacks gloss and shine, otherwise you should use a good quality wax to add depth and protection.
All my previous motors were black and I used to use Meguairs Gold Wash and Autosmart Cherry Glaze polish ... my cars are ALWAYS gleaming. Now that I have a red car, im still using the same stuff and the cars looking mint!!
By the way, for the trims get this GEL type polish called MER ... AMAZING stuff to say the least, Ive used Meguiars Trim Detailer etc but nothing can touch MER Gel ... that stuff turns all the trim on my car back to black with a bit of elbow grease!
Ill give a big vote to Super Resin Polish. Just bare in mind it doesnt have much cut, ie in terms of removing sirls/scratches etc. It has filling properties and it more classed as a cleaner. Dont let that put you off, some polishes are just the same. I use SRP myself put it that way. However you can achieve better finishes by how you apply it. For example with SRP apply it using a Microfiber pad and work into the paint. After doing the car buff it off with a suitable Microfiber towel. You can apply several coats, some people have done some tests with using five coats and showing some impressive results at masking swirls. Better results in terms of appearance and longevity can be had by following it up with Extra Gloss Protection, also by Auto Glym. This is an oily based "sealant". Again if you want even more results you can add a good wax to it. Collinite products work well with the Auto Glym products mentioned above. After all that you should need a few days rest lol. I achieved great results in my mums '00 red polo. One of the wings had a respray job prior to us buying it and the lacquer has failed, the paint below oxidised and turned a lovely pink. The three products mentioned above after a good wash and clean produced some great results. With the wing turning back to red and damm that car is shiny! Hope that helps. Of course there are products out there, but thats just what I use and others agree works well.