3) Establish contact
Before you decide to proceed any further, you should consider rearming yourself. As you've probably noticed, there's a Mule vehicle here (#1). Use it and exchange your current weapon for a sniper rifle. Once this is done, start moving east (#2). I'd strongly recommend that you leave the rest of the team behind, because you'll be playing as a sniper for the next few minutes. As a result, you will have to be very precise in order to succeed.
There's a large crossroad in front of you. This area is being guarded by AT LEAST five enemy snipers. You will also come across a heavy machine gun post, as well as a few standard enemy units. As you've probably suspected, you will have to plan your EACH move very carefully. I would recommend by taking out some of the standard soldiers. They will be standing in front of you (#1). There's going to be two or three of them. Once they're gone, take out a single opponent who's hiding behind the sandbags. Check the second screen if you can't find him (#2).
Now we're going to have to take care of two enemy snipers. They are currently standing to your right. One of the snipers is occupying a roof of a closer building (#1). You will have to wait for him to reveal his position. The second sniper is a lot more difficult to find. Check the second screen if you're having problems with that (#2). Make sure that he's dead before proceeding any further. Otherwise he would have probably killed you.
Now you will have to take a look at one of the northern buildings. You're probably standing next to it, so you won't have to spend too much time searching for the sniper (#1). Once you know where he is, move to the right and try aiming at his head (#2), however make sure that you don't expose yourself too much, because there's at least one more sniper covering this area.
Like I've said, you'll have to deal with one more sniper. Check the first screen if you want to know where to look for him (#1). Make sure that you've taken him out from a larger distance, so you won't lose any health points. Now you will have to disable the heavy machine gun post (#2). The easiest way to do this would be to attack this soldier from the western ruins. You may proceed to the eastern part of the map (along with the rest of the team).
You will have to choose several narrow passageways in order to reach your current destination (#1). Despite what you might think, you shouldn't be in a lot of hurry, because you will come across new rebel units along the way. You should also consider ordering your teammates to stay behind. The first rebel soldier is standing on a top of a scaffolding (#2). Kill him quickly.
You will come across two-three new enemy units just around the corner. Most of the rebel soldiers will be standing near a large van (#1). It would be wise to allow the rest of your squad to take part in these fights. Once the enemies are gone, go straight. You are getting closer to a much larger square (#2). You must be careful here.
This square is being defended by two heavy machine gun posts. The first machine gun post is located in front of your current position (#1). It would be wise to use the scope. Lean out very carefully and kill the enemy soldier by aiming at his head (#2). He can't survive this attack!