What Should be done - Charge till 100% then drain till 0%
(Disconnecting every few days works too)
If you want to keep it plugged in - Remove the battery and keep it plugged so your battery dosen't go to shit.
What I do - If I'm gaming or something I remove the power bar and keep it plugged. Else I just generally keep it plugged and drain it every few days or so.
When I use to use my laptop all the time I had the battery in with the charger turned on. I learnt the hard way that, that's wrong. If you don't plan to move your laptop take out the battery and plug it into the wall.