Fallout 4

Here is a short video guide I made for all the locations of the magazines. I show a detailed walkthrough of each spot. Hope this helps!

NOT MY SOLUTION

Thought I put this here because I found it on Gameranx.com!

Scav! Magazine Issue #1: Galactic Zone – Find the Star Control building and follow the rounded exterior walls to a locked gate on the left. The Scav! magazine is found near a ruined bus, sitting next to a loot crate on the wooden boxes.
Reward: Increases speech challenge success chance.

Scav! Magazine Issue #2: Junkyard – On the western edges of the map, find the junkyard and go upstairs through the interior stairs. Follow the path around to a computer desk (just past the hanging yellow ride seat) — the issue is right there on the desk next to a locked safe.
Reward: +25% Combat Knife and Switchblade damage.

Scav! Magazine Issue #3: Kiddie Kingdom – Travel up to the northeast corner to discover the Fun House. Fight through the Hall of Mirrors and jump across the rotating platforms to reach the neon green spinners. Enter the tunnel on the right and continue ahead straight through another neon tunnel to find the issue in a dead-end corner.
Reward: +10% Hand to hand weapon damage.

Scav! Magazine Issue #4: Grandchester Mystery Mansion – Move down to the southwestern corner of the map to find the spooky mansion haunted by ghouls. Go through the whole tour and stop at the Exit sign — enter the employee’s only door (pick the lock) and take the stairs up to an abandoned workshop. Near the entrance to this room, look on your right to spot the issue on some wooden boxes, near a red handcart.
Reward: +5% explosives damage.
**NegativeCreep08 has mentioned that you need to have the ability to pick a Master Lock for this issue**

Scav! Magazine Issue #5: Dry Rock Gulch Theater – Enter the employee’s only area of Dry Rock Gulch and look for a pair of red cargo containers with wooden boards leading up to the garage roof. Cross from the garage roof onto the central building roof to discover the last magazine on a circular wood table.
Reward: +1 STR & +1 END if you have <= 10,000 caps / +2 STR & +2 END <= 1,000 Caps / +3 STR & +3 END <= 100 Caps.

EDIT: In the comments is a way to get #5 without finishing the story

SECOND EDIT: I am editing this 2 years later because I got a PM that I was an asshole for saying theater in issue #5. As it states at the top, I did not write this out. I simply posted it here for people to see. Also, I kept it as theater because the way to get into the employee's area without finishing the campaign starts at the theater, as I have mentioned. I have no idea why someone would take the time to personally PM me with a hate message over a solution, but here we are.

in this video i show you how to get all magazines at the start of the dlc
there is a glitch to get number 5 i show you in the video on how to get it

Dislodged Puma solution is great up until #5, as he states. For those who need better directions for #5 follow below:
Starting from the East entrance (where Sheriff Eagle is / nearby the Minecart Coaster) head just into the park until you reach the first street. You'll notice a giant red Nuka bottle tipped over before the first building on the left. Jump/climb it and head to your right. You'll notice a gap between the mountain peaks. Jump up the rock face up through the gap ( you may have to follow the rock face a bit to get higher ground. Jump up as you head to the gap. If you can't jump, step back slightly until you can jump again, then move forward in the air)
Once though the gap, head left and follow the the rocks until you get to the top of the wall. Once on top, turn right and follow the rock wall to reach the Employee's Area.