hi i am a valeter dont use it if its a ) a cheap one b) you dont really know what your doing if its a new car the paint can still be quite soft compared to older cars that sometimes require a buff with a good cutting polish, you could end up with large swirl marks in your paint if your not careful, just a friendly warning lol be wary of cheap buffers
Agreed - if you're unfamiliar with using one, do what a lot of newbies do when starting out with machine polishing - get an old panel from a scrapyard and have a practice. If you make an @rse of it at least it's not on your car.
Oh, and as has been mentioned - it really needs to be a variable speed random orbital to get swirl free results. If it's just a cheapy one that spins around with a wool 'bonnet' on, it won't do anything other than maybe putting in more marks in the paintwork.
The Meguiars G220 is a very good and universally rated bit of kit - you can pick one up for between £130-150