First of all, you will find countless opinions of "the best way" to maintain your battery, whether it be a phone, tablet, or laptop battery. In my humble opinion, if you just use common sense and use the battery as a normal person, you will not notice a difference in performance.
This is not to say that a number of factors do not affect battery lifetime. But in the long run, you will not gain much by being the "perfect" lithium-ion battery owner. The difference will be miniscule.
With that being said, leave your device plugged in as much as you want. Some say that is bad, and that you want your battery always within its "happy range" of 15-85% or some BS like that. Here's a personal anecdote: I've owned an iPad for 3 years. I also work every weekday. I don't bring my iPad to work...no need for it. I use it on the weekends and after work. The rest of the time, the iPad is on the charger. When I use the battery, I notice absolutely no degradation of the battery as compared to when I first purchased the iPad. In fact, the battery life I get on my iPad still impresses me and I am more than pleased with it.
In short, just use your device like a normal person and don't worry.
*Disclaimer: there are some common sense things to worry about, many of which were already mentioned, including don't leave your device in the sun, and be wary of 3rd party chargers since the amperage might differ. One more item that may not be very common sense but is important is do not use car chargers...the voltage in a car charger fluctuates when you start/stop the car and accelerate/stop accelerating, and the voltage jumps are very bad for the lithium battery.