Building skills:
In the Hub, there is a library where you can buy books to increase your Repair, Science, First Aid, Outdoorsman, and Small Weapons skills. These books can be expensive. Use the following trick to make them free:

1. Make sure your character has a good Steal skill (50%+)
2. Go to the Librarian, Mrs. Staple, and use your Steal skill on her.
3. Steal her Desert Eagle.
4. Trade it back to her for books.
5. Repeat steps 2 through 4 as necessary.

233 pistol:
Help the man in the falling down building towards the south of the Hub marketplace. Once the raiders are dead, he gives you the .233 pistol, one of the best pistol in the game.

Plastic explosives:
Plant a plastic explosive on someone, then click on your pip boy. Click on the little bell and rest for one or two hour. When the plastic explosive blows up, all their items will be on the floor, but you will not go in combat mode and the person will still be alive.

Gun classifications:
Small guns covers rifles and machine guns, not just pistols. Big guns only covers minigun, flamethrower, and rocket launcher size weapons.

Better armor class:
Note: This trick requires v1.0 of the game. Get a bag and some armor. Equip the armor, then enter the bag. Drop the armor off of your character, then pick it up. Repeat to build your armor class.

Fast caps:
Go to the casino/bar, talk to the black man wearing metal armor and hold 1 + 4. In about a minute you will have over 2,000 caps. You must have at least 55% on Gambling to get this amount. The higher the percentage, the faster you will get more money.