The Rebbe's guidance for travelers:
What to take along. Bring tefillin, a Tehillim and a Tanya on a journey, and study from them on the way; regular study of Chassidus is an essential obligation in our times (IK 7268).
Before and during the trip. Give tzedakah every day and add in Tehillim until the journey is completed (IK 7950). There is no need to worry about flying on a plane with four engines (IK 2928). Arrange a trip so as to be present for a special day such as Yud Shevat (IK 1336).
Travel according to halachah. Travel in a permissible manner according to the Shulchan Aruch — not on Israeli ships that sail on Shabbos (IK 9157).
See also: Shabbos and holidays – Keeping Shabbos; Land of Israel – Leaving Eretz Yisrael or traveling abroad; Prayer – Saying Tehillim (Psalms).