There isn't a way (that I know of) where your reputation score is shown.
There are alot of factors that contribute to how many points you give. It is based on your reputation score (which you can see on your main user
cp page, in the upper right corner of the recent reputation box. It is also based on the # of days you've been registered, the # of posts you have, etc.
There are a few other quirks spelled out in the FAQ, too, if this doesn't answer all your questions.