I'm a fed district court clerk. Here is my advice from my POV as a clerk (I've been the main clerk on a handful of trials and have helped with about five more) and what I've gathered from my judge and other judges.
1. Be organized. By that I mean know the record as best as possible. Nothing drives my judge crazier than asking for X document and the attorneys not having a clue where it is. Sure, you may need a minute or two to find it, but pushing more than a few minutes turns the courtroom a palpably awkward.
2. Be nice and courteous to everyone. This seems like a no-brainer, but we've had attorneys snap at court staff in and out of court. My judge has worked with his courtroom deputy, JA, and court reporter for decades. They're like family. He likes us clerks a lot too.
3. If it's a jury trial, lol at trial briefs. We'll read them to keep ourselves awake during trial, but they're not something to stress over. Conversely, if it's a bench trial, you better make sure those things are perfect. We will scour them and know them and the applicable case law thoroughly. (Anecdote: a case only the plaintiffs cited in a recent bench trial I worked on ended up 100% supporting the defendants to such an extent that the judge talked about it first thing in the morning on the first day of trial because it seemed to make the defendants' case a slam dunk. The case conspicuously settled at lunch. I have a feeling the associates working on that brief had a bad day.)
4. If you end up arguing before the judge, I wouldn't hesitate to somehow work "This is my first trial" into your response. Judges are human, so they'll be more forgiving of you than the partners you're with.
5. Research the judge. They have wildly different ways of handling cases that can (and should) significantly affect your approach.
6. This may sound obvious, but good god, listen to the judge's orders and don't waste everyone's time. My judge will really jump on attorneys and move them forward if they're not proceeding like he's asked them to.