You do not need a perfect build to make a good first impression in an Expedition. You need to know what the group is trying to do. Chapter 1 expanded Expedition parties to five players; the official global teaser highlights locations such as Krao Cave, Urugugu Canyon, Fire Temple and Draupnir. Different rooms will punish different mistakes, but the pre-run conversation is nearly always useful.
Say what kind of run this is
Is this a first look, a clean clear, or a reward-focused farm? Tell the group if you are learning a boss. Confirm who handles the first pull and who calls a reset. A short explanation before the fight is cheaper than five people guessing after a wipe.
Check three things before entering
Bring the recovery items you normally use, read the dungeon's current entry and reward rules, and make sure your most important defensive skill is on a key you can reach. Do not insist on damage at the expense of surviving a mechanic. When the run ends, name one issue to improve next time. That makes the next Expedition faster than simply requeueing angry.