Summary of some points I read on an article:
For storage: "Li-Ion batteries should be stored in a room temp or cool area neither at full charge or fully discharged. Around half charge has shown to be the best."
For longer battery life (for Li-Ion batteries):
1) Battery recycling is not needed, and some say it even hurts more than it helps.
2) warm temps will wear the battery more quickly
3) Life expectancy is largely based on how old they are more than how much they were used.
4) Keeping contacts clean is a good idea.
Also some other points in this thread:
5) Avoid 100% discharges of the battery. That is, when a ~4 hour capacity battery reaches an hour, maybe 30 minutes left, stop work and recharge.
6) Avoid Rapid discharge of the battery brought on by, for instance, long term CPU and video intensive applications, such as 3D gaming or longterm wireless downloads.
There are contradiction tho: MysticDude's & Crosstalk's experience contradict with point "3)"
A whole website on batteries: http://batteryuniversity.com/
Thank you all :)