I am done with fallout 4. I decided to play Fallout 3 , assassins creed black flag ect. So any cheats or tricks for 3? Lots of ammo , caps ect.

Well console commands are mostly identical to Fallout 4 (Elder Scrolls as well), so you have those.

https://ca.ign.com/faqs/2010/fallout-3-bottlecap-scrap-metal-gltich-exploit-1104091

This is an old well-known exploit for infinite caps and such. But the player.additem command would be a lot easier assuming you are playing on PC.

Well cheats are easy to google but some tricks:

You can get 4 Companions + Dogmeat + a regular companion by
*Go to Big Town and do as many quests as you can and finish them
*Go to Germantown and rescue 2 teens named Red and Shorty
*Go to Little Lamplight and agree to escort a guy named Sticky
*DON'T TAKE ANY OF THEM BACK TO BIGTOWN
*In the National Archives building on the DC strip help Sydney but don't go into the basement of the building just leave and they'll follow you
But if i remember right you can change their equipment and they're decent fighters but they're all non-essential so keep them safe!

*When you find Megaton on the right side of the town, outside not in town, there's a rock past some mole rats that has some loot in it, keep looking for big rocks, one of them is a container

*Some Companions need you to have evil or good karma before hiring them, steal junk or give tons of water to beggars for easy karma changes