Upvote: neutral / friendly contributions related to the topic, regardless of whether or not I personally agree (Exception; hate speech wrapped in nice words. I don’t care how “friendly” the sentence seems, if the message itself is hate speech of any kind then donvote and/or report)
Nothing: Contributions that are friendly but off-topic, accidental duplicate posts, and stuff I don’t understand.
Downvote: Spam, scams, troll posts and hate speech of any kind.
I never downvote people just because I disagree. On the contrary - different opinions but discussed in a civilized manner, that’s an upvote from me.