What is the best way to sustain the life of a laptop battery?

1- Should I keep the computer plugged in while in use?

2- Should the charge be kept at 100% or close to it if possible?

3- Should I run the computer on it's battery only until it runs all the down and then recharge it?

4- Is it alright to use the battery in "high performance?"

5- Is there another alternative?

Any help I would be appreciated my a lot of us. And thanx in advance.