A) We are all new to it at some stage, as I state further down. To be honest I prefer people who have at least tried it themselves so know what it feels like, this gives you a good idea on how the bottom feels in this position.
All bottoms are entirely different on what they can take implement wise so treat each one as an individual (every bottom accepts spanking/C.P differently), go easy and build up, everyone and I mean everyone hates someone who starts out hard, it ruins the session plus the mutual enjoyment is lost due to it numbing the bottom, therefore, nothing is felt PLUS this is very dangerous if the Top isn't paying attention because this is when bruising and marks appear, so please be aware.
Also you need to pay attention to where your slaps, smacks or strokes are landing (unless the bottom specifies otherwise) you should stick to the area in the middle of the bottom, never go above the coccyx this is too high and you shouldn't use downward strokes with anything at this point either, I personally hate anyone using downward strokes with anything anyway it doesn't feel right and is very annoying when it hits the top of your bottom bone constantly. The other factor is how the bottom is positioned i.e. over the knee is a great position the bottom is nicely relaxed (unless they tense it up) it has what I call a rebound wobble when you spank it correctly, however, bent over puts a whole new perspective on it, the bottom is a little more taut and then to bend and touch your toes totally tightens all the muscles up thus making it easier to bruise, mark and sometimes cut, so ensure you use the implements with care.
Try not to go too far round the sides this is called wrapping and is extremely painful. In my opinion any implement over 6" in length should be used across both bottom cheeks, to attempt to use it on either cheek will result in 1) it hitting the bone in the centre of the bottom 2) wrap on the opposite cheek. Think of a 4 strap suspender belt and how it frames a bottom, this helps to keep in target, a couple of inches lower than where it fastens at the waist and not past the side straps and above the thighs of course, in essence aim for the roundness of the under cheeks.
All that is really needed is a little care and attention, ask the person with whom you are playing if it is okay, they aren't going to snap your head off, I am sure they would rather feel safe and trusting than be marked for weeks. Also be aware of dangers as a Top ensure the bottom is ok throughout, I don't play with anyone who has been drinking alcohol as this numbs you from pain, as I don't play with anyone who takes drugs or pain killers all are pain dullers, if a bottom has to take these then that is just masochistic and they shouldn't be playing at all because the whole idea is to revel in the spanking, as a Top you should take control and not play with any bottom you deem inappropriate to be over your knee.