Step 1: Put alot of points into stealth skill and a prefferred fire arm type (small guns, melee, whatever)

Step 2: As soon as you can complete the Operation: Anchorage

Step 3: Get the chinese stealth armor

Step 4: Crouch

You can now defeat basically anyone, at any time, with little to no warning. but by now you're probably done with fallout 3 anyway and waiting for new vegas

hey buddy, you forgot silent running!