Batteryuniversity.com has written a detailed piece explaining ways to prolong lithium-based batteries. These are the key points one can take out of this write-up.
1) A lithium-ion battery in use typically lasts between 2-3 years. Avoid frequent full discharges because this puts additional strain on the battery. Several partial discharges with frequent recharges are better for lithium-ion than one deep one.
4) Removing the battery from the laptop when running on fixed power protects the battery from heat.
The entire article can be read here.