The only choke point that comes to mind in mission 1 is the dormitory shootout. When you first enter, crouch down and try to get a headshot on the guard. It is imperative to get an assault rifle ASAP. Sprint to the other side and up the stairs. Always take the shortest route to the next set of stairs and you'll avoid the QTE's with the doors. When you get the top floor, there will be at least 4 VC below you. Take out any in your line of site and sprint to the finish.
Afterwards, travel to the bridge through the buildings. Dont get near the mounted rifle until the bombs go off. After that, it's a quick mounted gun scene at the end and you're golden.
PRO-TIP: You have to leave out of the door you came in from when the room fills with gas.