Be gracious with table talk. Don't gloat or rub good attack rolls in your opponent's face (shouting 'dakka! dakka!' doesn't help)

Some of the best players I have gone up against were very humble and even self-deprecating during the game.

If there is a collision/range/fire arc dispute, just roll for it and move on.

If you finish your game early, don't distract people who are still playing with your spectator commentary.

If you have 3rd party acrylic tokens, make sure your opponent knows which token is which before the match. (I have acrylic everything, but I bring my old core set cardboard to tournaments just in case someone objects to me using acrylic range rulers/maneuvering templates)

The Kommander brings up some very good points. Jumping up from the table, doing a victory dance and screaming " In your face! " should be considered poor form.

And as for the spectator commentary, absolutely not. We have very few rules at our local club in order to keep things casual, but this is the biggest one. No one is allowed to make comments or suggestions on a game in progress. It's not their game after all. I painted some modern tanks of mine in a nice camouflage pattern that blended perfectly with my scenery, and during a game managed to move them to the edge of a wood. My opponent didn't notice them until someone decided to point them out to him. My ambush was gone before it started.

If it's not your game, keep your comments to yourself, unless you're asked.

If you have alternative tokens that might be confusing, best use the core set ones to avoid dramas.

Go into the tournament with the mindset that you are there to have fun and enjoy yourself, and play fair, and you should have a successful tournament.

When damage equals an amount sufficient to destroy the opponent's ship, do you still deal the cards and immediately discard them, or just leave the damage deck alone?

Technically you are required to deal the cards, even though it makes absolutely no difference (unless it's a case of a crit applied to a ship at the same PS that hasn't attacked yet). Some people don't know how probability works and will get upset if you don't follow this rule.

If two ships are touching, and they perform the same unobstructed straight or K-turn move, are they reasonably expected to still be touching, thereby blocking one of them from Actions?

Actually it's the exact opposite. If two ships are touching and perform the same straight maneuver they will be touching, not overlapping, and suffer no action penalty. The tournament rules even explicitly state that in this situation the two ships are considered to be touching, not overlapping, even if inaccurate measurement causes them to appear to overlap.