Zaino is excellent. It is a lot of work in the beginning, but the results are incredible. Please note, Zaino isn't a miracle worker and it isn't going to make bad paint look good again.
As for the clay, I use Clay Magic, you can get it at your local parts store, it's sold in a few different grades though. I'd suggest, for starters, get the mild grade (less abrasive). You can also buy a particular liquid to help ease the friction when using, but I've found that cheap window cleaner also works well.
Once you clay a car, you must then wax the snot out of it in order to get your shine back. And as mentioned above, as long as you constantly massage the clay, you will not tear up the top surfaces of your paint.
You can feel the difference immediately.
My Dad always said I'd get sued by a fly because they couldn't land on my paint, it was so slick
