I roughly follow the following (prioritized) rules:
Up-vote if I want to see more posts like this/down-vote if I don’t want to see more posts like this, regardless of the current total.
A comment that I do not feel very strongly about I may up- or down-vote based on what total karma I expect the comment of this kind to deserve.
Very occasionally, I might like or dislike the author for unrelated reasons, and decide to up-/down-vote based on that.
I roughly follow the following (prioritized) rules:
Up-vote if I want to see more posts like this/down-vote if I don’t want to see more posts like this, regardless of the current total.
A comment that I do not feel very strongly about I may up- or down-vote based on what total karma I expect the comment of this kind to deserve.
Very occasionally, I might like or dislike the author for unrelated reasons, and decide to up-/down-vote based on that.