The train station itself has a table containing the radio that will summon the rescue. The drop into the train station is one-way, so make sure to jump as a team to prevent a tardy player being snagged by a Smoker. Once the Horde is cleared out, take the elevator up as a team (a ladder will also retract up the wall in case anyone missed the elevator) onto a roof overlooking the cramped train station. The easiest way to handle the Horde is simply to retreat back into the safe room, but the side room closest to the button is also relatively defensible, especially if the table with Tier 2 weapons spawned there. Pressing the button starts the elevator lowering, but also summons the Horde (it is at this point that Special Infected are likely to start showing up). This table might spawn in any of the rooms. Before pressing the button be sure to locate a table containing an Assault Rifle, Auto Shotgun, Hunting Rifle, and an ammo pile. A flight of stairs leads up to the second floor, where the button to summon the elevator is on the wall next to three interconnected rooms. There will be a few Common Infected loitering about that are easy to dispose of. The safe room door opens to a small hallway that overlooks a small courtyard and the raised elevator. The Survivor Bots will always grab the following weapons. You are not going to survive the zombie apocalypse by yourself. In all cases, watch out for each other and take care of each other.
Communicate with your teammates, if you're playing with others, or if you're by yourself with the AI, point out things they might otherwise miss.
Left 4 Dead is supposed to be a cooperative game. Being observant might alert you to something nasty ahead of time, like a Witch, Special Infected or Tank, and allow you to prepare yourself.There are, of course, a few key things to always remember: All campaign walkthroughs are done on Normal difficulty in single player, and are meant to give tips on what to do and generally point out things that might otherwise be missed.