Collect hidden Bobbleheads in the corresponding locations to add +10 skill or +1 stat:

STAT - LOCATION
Agility - Greener pastures disposal, in the office
Charisma - Vault 108, in the cloning lab
Endurance - Deathclaw sanctuary entrance
Intelligence - Rivet city, on table in the science lab
Luck - Arlington cemetery north, in the basement below the stairs in the arlington house
Perception - Republic of dave, on a bookshelf in the museum of dave
Strength - Megaton, in lucas simms house

SKILL - LOCATION
Barter: Evergreen mills - market bazaar
Big Guns: Fort constantine - CO quarters
Energy Weapons - Ravenhold
Explosives: WKML broadcast station - sealed cistern
Lockpick: Bethesda - Bethesda offices east
Medicine: Vault 101 - Dad's desk
Melee Weapons: Dunwich building - virulent underchambers
Repair: Aerefu - Evan kings house
Science: Vault 106 - Living quarters
Small Guns: National guard depot - National guard armory
Sneak: Yao guai tunnels - Yao guai den
Speech: Paradise falls - Euology's pad
Unarmed: Rockopolis - Head directly west from casey smith's garage, look for tattered banners strung up