Note: Using the "Infinite XP" glitches can leave you weak. The higher level you are, the more difficult the game gets. You will encounter more and stronger enemies, and they will have better weapons in better conditions.
Have a Speech skill of at least 30. Visit Big Town by travelling northwest from Springvale Elementary. Talk to Bittercup about her dating exploits. Talk with Pappy about how he came to Big Town with Bittercup to start a Speech challenge. If you fail, the challenge will still be available to retry. Repeat the challenge until you are successful. You will get six experience points, and the option to retry the challenge can still be selected. Repeat the challenge as many times as desired. Note: This requires the unpatched version of the game.
Be at least level 10, and have a 60 Sneak skill. Unlock the Mister Sandman perk. Go to the Smith's house at Andale. Sneak upstairs at night while everyone is sleeping. Try to pickpocket the boy, but instead select "Murder". You will not lose Karma and gain over 50 experience points. Because the boy does not actually die, you can repeat this as many times as desired. Note: The game may glitch and become unresponsive. Also, this requires the unpatched version of the game.
Note: This trick requires you take the "evil" path. After agreeing to help Mr. Burke nuke Megaton, go into every single house and steal everything (any little piece of junk you can carry). Sell them to the local shops (Craterside Supplies, The Restaurant, Moriarty's Saloon, etc.). If a particular house is locked or you need a key to get into a safe or something of that nature, just kill the owner of the property, and get the key from his or her body. Kill everyone in sight, especially the shop owners because you can get access to their entire inventory, plus the Caps that you have already spent on them. Kill every one and collect everything to leave Megaton empty. You should have at least 600 caps. Remember to sell some of the things you gather to the shop owners because you cannot fast travel when over encumbered. This can be done in almost any town you visit. To avoid getting over encumbered, get all the supplies that you can possibly carry, then drop the rest just outside of Megaton. Fast travel to Rivet City or some other marketplace. Sell what you have, then return to Megaton, and repeat the process.
In the "Strictly Business" quest, capture Susan Lancaster, and get your reward for her capture. Afterwards, speak with her in the slave quarters part of Paradise Falls. Note: You will need one of the slaver's keys to access the slaves quarters; pickpocket one. After entering the slave quarter's, speak with Susan. When she asks for help, choose the option "You're a slave. Deal with it.", then return to Grouse to collect the reward again. Grouse will think that you captured her again. You can repeat this as many times as desired to get 250 Caps and a slave collar each time.
Save all pre-war books you found (not scorched or ruined). Go to the Arlington library. At the southeastern corner, you can find an NPC that will buy those books for 100 Caps each. You will also get 10 experience points for each book you sold.
Save the game before starting a dialogue with a Speech bonus, hacking a computer, lock picking, or pick pocketing. Then, simply reload the game if you fail the challenge.
Use the following trick to avoid breaking bobby pins when trying to pick a lock. Just before the bobby pin is going to break, exit that screen, then go back. You will save a lot of bobby pins by doing this. This also works when trying to get a password for computers.
You can find a sniper rifle and other supplies hidden in a rock near Megaton.
There is a hidden area in the National Guard Armory that contains an experimental MIRV gun (the most powerful weapon in the game) and the Small Arms bobblehead.
When wandering around the world or towns, use the following trick to get an early notification on enemies, encounters, or who is nearby. Keep tapping [V.A.T.S.] while searching at all angles. If there is something out there, you will get the V.A.T.S. zoom in with a low score. You will at least know what is there and can figure out a plan of attack or how best to sneak around it.
Dogmeat is found in Scrapyard. On the world map, Scrapyard is in the top right corner of the square that is two squares directly below Minefield. Follow the clear triangle on your compass if you are having problems finding it. Enter Scrapyard, and look/listen for fighting. Your will find Dogmeat fighting a Raider. Once the Raider is dead, you can talk to Dogmeat and ask him to join you.
If you talk to Jaeriko about going back into the wastes, he will join you if you give him 1,000 Caps for supply money.
The hidden Vault-Tec Bobbleheads can be found at the following locations. Collect a Bobblehead to gain +10 to a skill or +1 to a stat.
Stats
Skills
There are five Super Mutant Behemoths that can be found and killed. After they die, they will not respawn. You can find them at the following locations:
Evergreen Mills: At the bandit camp near Vault 112, a Behemoth is behind an electric enclosure beside the train tracks. When the generator powering the enclosure is destroyed, the Behemoth will escape.
Galaxy News Radio: This Behemoth will destroy a wall just outside the GNR Building as you enter the area (quest related).
Jury Station: Go west until you find a group of crumpled up train cars. Search this area until the Behemoth appears. You will know you are in the correct area if you see a teddy bear in a shopping cart.
Takoma Industrial: Located east of the GNR Building at the end of the map. The Behemoth is just north of the factory, standing in the middle of some wrecked cars.
The Capitol Building: Use the west entrance, and go inside the main room. Look on the map. The room is straight down the hall from the entrance. However, debris will force you to find an alternate route there.
The code to activate Project Purity at the end of the game is "216".
Move north and slightly to the west of Minefield. You will find the VAPL-66 Power Station. Follow the power lines north until you hear a radio signal Athena. While staying in range of that signal, search the surrounding rocky area until you find the ship.
The house with the Luck bobblehead also contains a hidden shrine to Abraham Lincoln.
When you discover the identification of the android and are deciding to turn him in or warn him, go to the android first. Convince him to go to Zimmer on his own, and he will reward you. After that, go to Zimmer in the science lab. Tell him about the android's identity. He will also reward you. Note: You will still get bad karma.
Run up a steep hill with the robot at the bottom. Some robots have problems shooting upwards at a steep angle. Shoot at them as you are running up the hill to destroy them easily.
Enter the museum, and examine the notice on the wall terminal to the far right. The text is about a virus infecting their Archetype, and at the end, it repeats parts of the song "Archetype" by Fear Factory: "the infection has been removed, the soul of this machine has improved."
Use the "Infinite XP" Speech trick to easily get the "Silver Tongued Devil" achievement.
Accomplish the indicated achievement to get the corresponding number of Gamerscore points: