I will give positive rep for a wide variety of reasons, most often to someone just starting to post on CD. I will also, like Ed and Sam, give positive rep if I think someone has received negative rep unfairly. I'm more inclined to give neutral rep rather than negative rep if I think someone needs negative feedback on a post, but most often I'll send a pm to the poster.
I will look at rep in conjunction with post count prior to reacting to a post that is written in a fashion to be non-helpful to the CD community, but other than that, if you are a middle of the roader and building rep in a slow and steady fashion, you are good to go!
