Keys are for Cowards

Keys are for Cowards is an achievement/trophy in Fallout 3 which is awarded for successfully picking 50 locks.

Hints

 * 75+ Lockpick skill is an advantage.

Places with many doors to lockpick

 * Megaton - Try going here at night. Various houses are easy locked and can be lockpicked easily. Also check inside, as there are some locked objects in the houses as well. Ex: Cash Register, Refrigerator, etc. You will lose karma doing this.
 * Minefield -There are a few doors you can pick here. As well as a safe under the bed of one of the houses. Also, one of the 3 buildings contains a dollhouse that you need a lock pick skill of 100 to open.
 * Rivet City - At night. The door to Rivet City Market, and a decent total of doors on the Upper Deck (most of them are easy locked as well) like Sister's Hotel Door, Hotel Room Door, Zimmer's Hotel Door, Doctor Preston's Door, Flak & Shrapnel's Door, Doctor Li's Door.
 * The Midship Deck has a few: Seagrave Holmes' Door, Door to Rivet City Market.
 * Tenpenny Tower - Cash register.
 * Underworld - Cash register, Safe. (Both hard locked, and both located in Carol's Place)
 * Little Lamplight - Two easy locked ammo crates in the middle of the Great Chamber.
 * Capital Wasteland - Exploring and scavenging every single building you come across can be very helpful, many buildings contain at least three locked containers and one locked door.
 * Super-Duper Mart - The mart contains lots of locked ammo containers scattered all around.
 * Vault 87, Vault 92, Vault 106 and Vault 108 - These vaults contain lots of locked doors, decent amount of locked metal boxes/first aid boxes/ammo boxes.
 * National Archives - Various safes in the lower levels containing documents.

Exploit
There is an entry to the Broken Bow of Rivet City south west of Rivet City across a bridge. The door is locked "Very Hard" (requiring a Lockpick skill 100) on both sides. From inside, there is a power switch to the right of the door which unlocks and relocks the door. If re-locked via the trigger, the door will drop to "Easy" for unknown reasons. You can re-lock the door and pick or force pick (85%) it an unlimited number of times for an easy achievement.

(PC Only) If you just want the achievement and don't care to cheat, then find a particular Lock preferably a "very easy" lock and unlock it then using the console command select it by clicking on it while the console command is up and use "lock" and then unlock it again, repeat until goal is reached.