[Perfectlap]

claying is something people don't do enough of. Particularly with ver soft German paints. Some go right to the polish route when a good once over with clay will do.
During the life of its paint you should polish and de-swirl as little as possible.
(Which means not touching the paint when its dry and limiting your washes)
There are different grades of clay. Some very soft for monthly use and some harder grades for stripping everything down to prepare for de-swirling and polishing.
Personally I think its very bad practice not to clay before doing any type of rubbing on the paint surface. Washing alone often does not dislodge the sediments blown onto the car from the road. Once you press against the paint with a wax applicator those sediments break loose and voila--sand paper.
the most important thing to do when claying is to really flood the panel with a very slick lubricant or suds. And keep a smal soapy bucket or tray to rub the debris off the clay before you fold it for the next panel. You can get Clay Magic Blue for $10 at most online detailing sites like openroadmotoring.com or detailcity.com I often see at Pepboys as well. Sonus makes the softest clay (green) I've tried intended for frequent use.