I am a parent/volunteer. My son is a junior so this is my 3rd year as a judge. I did not debate in High School or College. I have judged PF and LD. I prefer LD in terms of the time it affords debaters to develop an argument and that it can includes philosophy.

Use good evidence--meaning use reputatable sources (peer-reviewed is better) with proper citation. Have your evidence ready to show your opponent should they ask for it.

Clarity above all else. Speak clearly and direct your speeches me. In cross, direct your questions to your opponent. I like roadmaps (off-the-clock) and "sign-posting" within the speech to help with my flowing. Be clear in your arguments in terms of how you are linking everything together (claims, warrants and impacts).

In terms of speed, talking faster than 300 words/minute (wpm) you do at your own risk. I read at about 300wpm. Most audio books are read at about 150wpm. Anything being read faster than 300wpm is faster than most auctioneers. I find "spreading" to be a lazy tactic--trying to throw everything you can at your opponent also means you want the judge to sift through your pile of arguments as well. If you speak faster than 300wpm, then you run the risk of me not catching the important parts of your argument.

Opponents should be respectful. I understand the adreniline can get flowing, but being abusive or sarcastic won't help your cause.