What's the best way to charge and discharge gadgets like your phone and laptop to improve or keep as much battery life as possible in the Long Term. I've heard many theories but many of them conflict with each other. I'd like to find the final answer.
laptop, just run the bat down to like 10% or so every other week
With Lithium Ion batteries the best way to use them is just... by using them normally. They don't have any "memory" effects like the older NiCd batteries so you don't have to pay attention to charging cycles etc. The downside is, the Lithiums will age, no matter how well you treat them, and eventually fail. But there's no way around that as of today.
By normal using I mean - let the device go somewhat empty before charging, and don't leave it for long periods plugged in for charging. Don't let it go so low that the device shuts down itself though, even though there's a safety circuit that prevents the voltage from dropping too low inside the battery it's unnecessary to let that happen. The Lithium cells die if their internal charge becomes too low. Also, if you plan to store a battery and not use it, make sure to charge it up before that, never store it empty.