North Hall

Enter through the doors here after tagging a couple of enemies via the snake cam. You may want to keep your suppressors on here, as a goodly number of soldiers will come your way if alerted to your presence via gunfire. Regardless, make your way into the building, head down the steps into the foodcourt, then come up on the other side to reach the upper area of the hall. That will lead into the bathrooms above the food court proper. Enter via the left bathrooms, use a snakecam on the far door to tag some targets, then frag and clear. That'll let you take over the turret here and use it on the remaining terrorists, should you wish to do so.

You won't get too many opportunities to fire away at your enemies with a turret, so take advantage.

A couple more long hallways will lead you to refit stations. On the way, be sure to duck into the three-doored room; it'll have more baddies for you to kill and the far door will act as temporary cover while you proceed onward.

Monorail

When you reach the monorail, get ready for a fight. There are two enemy turrets set up overlooking your approach, in addition to a huge number of soldiers that will be coming your way, some with shields. There also isn't a huge amount of cover, either, so you'll need to proceed quickly up one of the sides of the area, with your team following you, to flank the turret gunners. Otherwise they'll simply be replaced by other soldiers as they come forward. Alternately, you can simply sit back and shoot away from good cover until the enemies stop coming.

Assaulting the monorail is a tricky business.

When you're ready to move on, find the stairs off to the side of the main entrance to the monorail; they should be off to the right. This will lead you into a small bar. Clear it out, and take out as many enemies in the nearby entryway as possible, but don't enter it. Instead, head into the small access hallway nearby; this will let you flank a turret gunner and take him down without much risk.

After proceeding through the locker rooms (in a monorail station?), you'll come to the waiting room. There's another turret gunner here, but there are two doors, so you should be able to breach and clear at one of them after snakecamming to look for a shielded enemy. Your teammates will clear the bulk of the room on their own; just make sure that they're behind solid cover. Only one of the two escalators here is functioning, and as you approach it, enemies will start to come down from above, so be sure to keep your teammates close by.

Actually heading up the monorail's escalator will be a tricky subject, since most of the enemies near the bomb won't spawn in until you're almost at the top of the escalator. Send your team upwards first so that they wind up near the top of the steps, which may spawn in some enemies. If not, head upwards until you hear gunfire start cracking, then turn around and throw grenades or incendiaries through the small gap between the railing around the escalator and the glass ceiling. You want to be throwing near the waypoint marker on your HUD, as that's where most of the enemies are. If you're lucky, you'll catch a few of them with your nades without blowing up the bomb itself.

Send your teammates up the stairs first here.

When the area is a bit clearer, charge up and eliminate any remaining foes. Again, this can be tricky, as there isn't much cover and there still might be a few enemies around; try to duck behind whatever you can to improve your defenses while your teammates deal with the foes. Keep an eye on the windows near the bomb, as more enemies will be rappelling down. As your teammates work on hacking, head out onto the little platform near the bomb and shoot at any more rappellers. When the bomb detonates, climb up the ropes to meet up with your helicopter.