You’ve probably heard some people say you should drain your battery completely before charging it, but that applies to older nickel-based batteries.
Most of your gadgets these days will run on newer Lithium Ion batteries. Lithium batteries last longer when you shallow discharge, and keep them cool.
The gist is: Don’t drain your battery all the way, and don’t overcharge or overheat them.
I’ve set my low battery indicator to 50%, reminding me to plug in well before the battery is drained. Honestly, though, batteries have a finite life no matter what, and your efforts will only go so far, so don’t stress about it too much 🙂
If you’re interested in the power capacity of different battery technologies, real and imagined, see the graph below for a bit of detail.