There is alot of informaiton out there regarding light scratches, SMR use, do a search and you will find a wealth of information out there. Also, be sure to get DavidB's ebook - there is alot of good info regarding scratches and how to remedy the issue.
The goal of using SMR is to minimze or remove the scratches from your paint. Protect with a sealant and if you like layer with a good wax. Once that is done a good washing technique will minimize any future scratching, swirl marks, etc.