I just had mine done last week.  I did a lot of research about it first to find out as much as I could.  I had the hood pierced not the clit itself.  I had a verticle piercing which is much more about pleasure than the horizontal piercing.  The curved barbell sits right on my clit, and it is barely noticable unless I am having sex then holy crap!  The little ball rubs my clit in all the right ways!  It was painful for the first two days, but now (one week later) I feel no pain at all.  No body fluid transfer for at least two weeks, and if you do you have to soak it really well after in salt water. (my piercer was a realist, and said that clean hands can be used on it as soon as it feels ok, same with vibrators.  Ejaculate and saliva from your own partner is 2 to 4 weeks depending on how you heal, but as far as foreign body fluids wait 6 weeks.  She also said if you feel no pain when you are having sex, then go ahead, but no body fluids for at least 2 weeks.....)  There are two common ways to pierce, a clamp and a receiving tube.  The clamp is painful all by itself, the recieving tube goes under the hood to the right point, and protects your clitoris from the piercing process.  I chose to find a piercer who uses a recieving tube.  Perfect placement, and honestly worth the effort:)

For all piercing related info of the entire body go to safepiercing.org.  Its the association of profession piercers.  Lots of information and safe places to go.  Though its a USA site.