Documents first: passports current, any required travel authorisation confirmed, and a shared understanding of who is holding tickets and confirmations. Confirm arrival windows with enough buffer that a delayed flight does not turn into a stressful first hour together - punctuality and calm handling of delays matter as much abroad as they do on a local first date.
Discretion about the trip itself is worth a short conversation on its own. Decide together what, if anything, either of you tells colleagues, friends or family, and keep that answer consistent. A brief call the evening before departure - confirming the plan, the meeting point and what each of you is bringing - removes almost every source of first-morning confusion. It is a small habit that carries the same courtesy shown in agreeing who chooses the venue and who settles the bill on an ordinary date, simply applied to a longer weekend.
None of this requires elaborate preparation. It requires the same directness that made the arrangement work in the first place: say what you can realistically offer, confirm the practical details early, and leave nothing to be assumed.