Experience - I am a coach, though we specialize in congress and public forum. I have coached and judged LD before, though it has been a while (about a year). As for techniques and terminology, I know most of them -- and if not by name, through context.

General - Build me a good case - solid framework, well supported: convince me.

Evidence/data is good but is not my sole judging criteria. Logical argumentative techniques bolstered by evidence is your best route. Make sure I can follow (flow) your organization - signposts, transitions, etc.

That case should also be well-communicated. Impressive as a spitfire stream of data is, that's not effective communication. Abraham Lincoln and Stephen Douglas didn't spread; neither should you. I don't mind some speed as I know there's a lot you want/need to say, but again, make sure I can flow your argument. The faster you go, the less I can flow.

Be civil.

Judging/Win - I vote on argumentation and impacts first, evidence second, structure and delivery third, and civility final. A weak speaker with a solid organized case will win before a strong speaker with a weak or disorganized case.

I also don't disclose unless required and generally only give comments orally at the end of the round if something stands out as really weak or really strong and it is necessary to fix or continue into the next round.