I thought of a voting tip that I'd like to share: when you are debating someone, and one of your opponent's comment gets downvoted, don't let it stay at -1. Either vote it up to 0, or down to -2, otherwise your opponent might infer that you are the one who downvoted it. Someone accused me of this some time ago, and I've been afraid of it happening again ever since.

It took a long time for this countermeasure to occur to me, probably because the natural reaction when someone accuses you of unfair downvoting is to refrain from downvoting, while the counterintuitive, but strategically correct response is to downvote more.