I go to a user, scroll through their contributions to the site. If I find something I think helps users out a lot, I upvote them.
For some reason, I like visiting user pages, especially higher rep ones, looking at some of their contributions, and if they are really good, I will upvote.
Will this trigger a serial voting ban if I do it too much? I don't just blindly upvote/downvote, to make it clear, I do it based on the size of the contribution, but most top users have lots of Qs and As, and I don't want to get banned.