How do I make my laptop's battery last as long as possible?

I’ve recently purchased my first laptop and I’m concerned about the battery life. The laptop in and of itself was appraised to have a great battery life, but of course it won’t be as good as said in use.

I’ve heard many contradicting things about keeping the battery life at the top of its game. Some say to keep it plugged in all the time, others say to only plug it in when necessary.

What do you say?