Sometimes passengers are taken across the tarmac in a motorized transporter. If this happens to you, before entering try to determine wheter it is a LIFO (i.e. Last-In-First-Out) or a FIFO (i.e. First-In-First-Out) model.

Most airport standing-only transporters with large doors in the middle are LIFO models (hang back during loading and get on only at the last moment).

When encountering FIFO transporters (usually ones with a primary entrance next to the driver and lots of seats on a long aisle), get in as quickly as possible and sitnear the front.

(from the the airline Passenger's Guerilla handbook, ISBN0-924022-04-3)