Mine is to accept almost anyone I know as a friend.
However, any 'friends' who
1. never comment on my stuff or
2. never reply when I comment on their stuff or
3. have a lot stuff I don't like to read in my news feed
get hidden. (As you can see, the key term in my policy is 'stuff' ;-)
But don't worry. Hidden people can come back off the hidden list with good behavior.
Just put this in a status message, but I wonder how many people have me hidden. Sick of weight loss updates yet?
Things that make you go hmm...