The Bobbleheads are really fun to find. Most of the time. I found the last one last night and got the "...they're action figures" achievement for a cool 20G.
So, I thought I'd post an article about their locations. Read on, if you're stuck, if you want to find them by yourself, you don't have to continue.
1. Perception: Museum of Freedom
When you come here for a Minutemen quest, be sure to pick the Bobblehead after rescuing the men inside. It's in the same room. There is also a magazine you shouldn't leave without.
2. Charisma: Parsons State Insane Asylum
This one is tricky because you need to find a certain NPC and meet his spawn requirements.
North East of Malden Middle School, you'll find the Insane Asylum. The guards are over level 20, so don't attack until you know you can at least kill one of them. You must also be over level 10 for the quest to trigger.
Once you've done both of these, you need to find a Ghoul called Edward. I found him in the bar at Goodneighbour and my friend found him at the Dugout inn at Diamond city, so it appears he gets around alot.
Once you've talked to him, he'll trigger a side quest. Follow the three quests til you get in to the Asylum. Follow the main mission path, til you find a lift face the lift and look right towards the desk and the bobblehead is there.
3. Explosives: Saugus Ironworks
This is a difficult area. Mainly because the boss inside is annoying to fight until you're around level 30. Anyway, once you've killed the boss on the highest level, walk up behind where he originally spawned and find the bobblehead on a shelf. Suagus is located directly east of Malden centre.
4. Science: Malden Middle School
When you enter you need to deal with a lot of gunners inside the building. Clear them out first, as they keep getting in the way anyway. It's on the extension of the second floor of the basement. You'll come to a lift on the first floor, take that down. You'll come to two lifts. Take the one on the left. As soon as it opens turn right and find the another access point. This will take you back to floor 2. Take the lift on your left as you exit the lift. You're now on the extension, now follow this path til you come to the exit. DO NOT USE IT. The bobblehead is next to it
5. Strength: Mass Fussion
You'll come here as part of the Institute questline. You'll have to clear out Gunners on your way through, with the help of Synths.
As you climb the building, keep looking out for a red sofa(couch), once you spot it, carefully jump ontop of it, if you jump to far, you'll fall to your death. Enter first person and pick up the bobblehead.
6. Repair: Corvega Assembly Plant
The Bobblehead is on the roof. You'll have to fight your way through everyone to get there. Once you've cleaned out the building and the roof, head to the circular tower at the back of the map. There is a sniper up there, so be careful as you climb. The bobblehead is on a crate just after you headshot the sniper. Corvega is North East of Greygarden and north west of Wattz Consumer Electronics.
7. Energy Weapons: Fort Hagen
Main Quest "Reunins" takes place here, so there is no need to rush to get this one. You can also use it as a dtarting point to get to the Repair Bobbleheads location, running North East towards Greygarden.
In the Command Centre there is alot to find. The bobblehead is in the kitchen, near there is a magazinr worth reading in a bedroom and if you find a toolbox on the southeastern side, you'll find the password to the master terminal. In that room you'll find an Fat Man.
8. Medicine: Vault 81
This is only reached via a side quest "Hole in the wall".
When you convince them to let you in, you'll be greated by a boy, pay him for the tour. Mingle around, talk to everyone, do a couple of misc onjectives (Katy's is most rewarding, you gain a magazine from it), then leave Vault 81. Mill about outside for a while, killing things or chatting up your companion and re-enter the vault. Go straight to medical, where there is a heated discussion going on. Agree to help to get the side quest "Hole in the wall".
Eventually, you'll come to a room that is Curie's prison. Agree that she can leave with you, and turn around, in the room with her is the Medicene Bobblehead.
9. Sneak: Dunwich Borders
If you've been to the museum of witchcraft, you may have already found this location, its west of that location and North of the Prydwen.
You need to descend in to the lowest chamber of the mine to get the bobblehead. There are loads of high level Ghouls in this location, including two legendary enemies. There are also lots of Gunners around too. The bobblehead is in the last room before you reaxh deep water that you can use to access a secret room with 3 mini nukes inside. You'll find it by the terminal.
10. Barter: Longneck Lukowski's Cannery
You don't have to explore far or even start the side quest in here. Do the misc objective by talking to Trader Rylee after her and Collins have stopped talking then talk to Collins. He'll let you look around. Climb to the offices. You'll find the bobblegead up here near a lock up with a terminal, there is a weapon inside. Not useful if ylu're already a high level, but it's an extra hack for the achievement. Located South of Museum of Witchcraft.
11. Big Guns: Vault 95
Only come here when you're working towards Caits affinity perk. After talking to her three times (the conversations she triggers) she'll ask you to go to Vault 95 with her to cure her of addiction. Inside there are assaultrons and gunners to kill. There is a bobblehead towards the back and you can get it early on. Enter the main foyer, turn right for the quest and take the lift. Take the right in to a corridor, where you'll find a high level gunner. Turn right where he and his buddies are playing poker. Go through the door at the back to find the bobblehead.
12. Small Guns: Gunner's Plaza
It's behind a master picklocking opportunity. If you have Master lockpicking available to you go ahead. But everyone else needs the key from the big boss at the top of the building.
Once you're through the door, kill everyone and find the bobblehead inside.
South of Shaw High School or Fallon's Department store.
13. Unarmed: Atom Cats Garage
If you've found this location, it is on the bonnet of a car in the main garage. If you haven't, it's east of Shaw High School. It also worth following the misc objectives here. It isn't an actual quest and give you a new location that'll be helpful to have soon. It counts as six misc objectives and allies you with the Atom Cats.
14. Endurance: Posiedon Energy
This is on the second floor but you have to up to the third floor to come back down, follow the path all the way to a boss in a big room, you'll find a bobblehead, a magazine and
A steamer trunk inside.
Not far away from Atom Cats Garage, travel south.
15. Agility: Wreck of the FMS Northern Star
There is a huge battleship from before the wall as you turn around from your fast travel port in to Warwick Homestead (this is the location you get from Atom Cats misc Objectives).
There are Raiders and Mirklire's to fight your way through. Once everything is dead, head to the bow, in a very dangerous location (like Mass Fusion) find the Bobblehead.
16. Luck: Spectacle Island
Swim from Warwick Homestead to the island you can see to your right. Once there, locate a green ship. On here you'll find the bobblehead. Be careful there is a mirklire Queen here. Kill her after to get progression towards another achievement.
17. Intelligence: Boston Public Library
Not far from Vault 114, Hubris Comic and Trinity Tower is Boston Public Library.
You don't have to go far. Turn left from the entrance. Killing turrets and protectrons on your way. There is a door directly behind them and the bobblehead is in the back of that room. You will have to fight Supermutants on your way iut though, if they beat the protectrons.
18. Melee: Trinity Tower
Listen to the Trinity Distress signal when the pipboy finds it. Follow the quest to the tower. Fight your way to the top and you'll come across a man in a cage. Let him out, walk passed him and Strong and you'll find the bobblehead on a desk. This quest also unlocks an companion Strong. There is also an trunk not far from the bobbleheads location.
19. Lockoicking: Pickman Gallery
West of the Old North Church (Railroad's base of opperations). You'll fight your way through loads of raiders til you come to a Mexican standoff. Either save Pickman or kill him doesn't matter either way and you'll find the bobblehead on the ground. Talk to or search the body of Pickman to get a key for a reward.
20. Speech: Park Street Station
It's the station next to the Boylston Club, where we freed Cait. The bobblehead is on the third floor, this is Vault 114, you'll visit here by Main Quest "Unlikely Valentine" so only come here with Nick Valentine. It's also worth noting you'll start on Level two. Following Nick around should lead you to the room with the Bobblhead inside. You need to hack a terminal to get inside. There is also a terminal and Holotape inside the bobblehead room.