Streets of Hope
Walk up the alley and you'll see a couple of Lenny's goons talking against a car. Wait for their conversation to end and then follow the guy that heads to the right. He will make for the scrap yards. The scrap yards themselves are restricted so you can't just walk in. Instead, just before the scrap yards, turn left to come up from the side of the house on that lot. Climb through the window and then walk through the room. Take cover behind the guard and wait for Gavin to continue past the guard.
Walk through the door just left of the guard and follow Gavin as he makes his way through the scrap yards. In just a moment, he'll walk between a broken down car and have a fence on his left. Come up behind him at this point and Garrote him. You should be able to kill him without being seen. Leave his body there and exit the scrap yards the way you came in.
Head back towards the pink car. When you get there, find the other two targets. One of them will make his way across the street to the shop just across from the garage. Make sure he isn't in there and isn't going in that direction. Find the door that has the guard nearby. There will be a shop keeper inside, looking directly at that door.
Go through the door and immediately crouch to break line of sight with the shop keeper. Now, hug the counter as you make your way to the back door of the shop. You should have no problem getting by the shop keeper. Go up the stairs to the apartment at the top of the stairs. You'll find a closet in the corner with some explosives next to it. Hide in the closet until the thug comes up the stairs. He'll walk into the corner to your left and stare out the window. Hop out of the closet and kill Tyler before he starts talking on the phone.
Make your way back down the stairs and out of the shop. Cross the street to the garage but don't go into it. Instead, there is an alley along the right side of it. Follow this until you find a small opening in the left side with a car sticking out. Walk up to the tail end of the car, crouch, and then walk into the building. Just inside will be a checkpoint. Go into the hallway and out onto the garage floor. Take cover behind the tires and when you are clear, go up the stairs. Be sure to watch for those that might be coming down the stairs as well.
At the top of the stairs, if you take a couple of rights, you'll be in a private lounge room for the garage. If you climb into a hiding spot in here and wait, Landon should come by at some point. When he does, you can simply strangle him and dump his body. Be sure to grab the Evidence from the desk here before leaving. Conveniently, this room has pretty good access to the exit as well.
Go to the other end of the room and on the right will be a door. Take the stairs beyond the door to enter a small garage. There will be a guard who doesn't move from the garage door to your right but there will be a mechanic that walks back and forth across the garage. Wait for him to stand next to the guard and then walk along the left side of the garage and outside. When you get back outside, go left so that if the mechanic comes back, he won't be able to see you. When the mechanic is gone again, sneak up to the exit ahead and pick the lock to get in.
Barbershop
Unfortunately, there doesn't seem to be a good way of doing this without using a costume. I've tried quite a few times but the second thug is only alone in a single room between two large groups of enemies that you can't sneak past.
Just off to your left will be a picnic table. Walk behind that and drop down off of the ledge. Quickly make your way down the rest of the stairs. Just to the right of the stairs will be another table with some beer bottles on it. Grab a bottle and toss it past the guard who is sitting next to the door so that he walks away from you. Subdue him and drop him in the dumpster. Since you are going to be using a disguise anyway, feel free to grab his if you like.
Not far from the dumpsters will be an oil drum with a wrench on it. Grab the wrench and cross over to the wall with the electrical wires all over it. On the left side of the wires, use the wrench to loosen one of the wires and then go over to the right and flip the switch to activate the wire. You can now leave and this will later kill Mason automatically. Go into the house through the door that is no longer guarded.
Make your way through the basement and at the far side, go through the door and up the stairs. At the top of the stairs will be a large living room with a bunch of guys in it. Avoid this by going through the door immediately to your left. Follow this into the barbershop and just inside on a shelf to your right will be the key disguise. Change into the barbershop outfit. Go up to the chairs and take a right to find a door that leads to the living room.
In the living room, walk straight ahead. You'll walk by a bar area with pizza on it and then find a door in the left corner that leads to a small room. The Evidence for this area is on the TV in the living room which you can grab quickly while in disguise. This small room connects the living room with the picnic area outside where they are grilling. Wait here and Luke will eventually walk through. When he comes through, wait until he's just about to walk outside and then strangle him to be sure that he isn't seen from the previous room. Take the body and dump it in the crate here.
Cross back through the living room and into the barbershop. Now just wait for Lenny to show up and subdue him when he sits in the chair. If Mason hasn't gone and urinated on the wire yet (resulting in his death) he should do so shortly. Just wait for him to die and once he is dead, grab Lenny and drag him to the front door of the barbershop.
