Good practices that can help to preserve its lifetime
There are 2 main types of rechargeable batteries: Nickel based and Li-ion batteries. NiMH (older batteries) are prone to memory effect while Li-Ion batteries do not have any memory effect. If you are using NiMH or NiCad (nickel based) batteries, then you will have to worry about memory effect. Most modern batteries are made out of Li-ion and therefore do not suffer memory effect. To check what type of battery you are using, just remove the battery and find for a sticker. The type of battery, voltage output and maximum current is written on that sticker. If you have a battery without any sticker or printings, the sticker may have fallen off OR you bought a really cheap battery. Note: this is pretty dangerous to your equipment. It may be cheap but the unstable voltage or current will degrade the quality of your experience and seriously affect the performance of your equipment.
Death is part of life
Pardon the language, but as gruesome as it may sound, this is our reality. Nothing escapes the clutches of death, even your rechargeable batteries. Your rechargeable battery does age and at one point, it will fail to supply the necessary energy to power up your equipment. But the million dollar question is, as owners of these batteries, can we delay its death? Yes you can, with good charging habits.
Memory Effect
Memory effect is a unwanted effect that occurs after a series of charging and discharging whereby the battery does not charge up to 100%. It would assume that the battery is full even though it is not. For Nickel based batteries, you'll have to fully discharge it before charging to avoid memory effect. Li-ion batteries, on the other hand are not affected by memory effects.
For Li-Ion batteries, do not do practice full discharge and full recharge often. Unlike Nickel batteries, this practice will damage and shorten the life-time instead. Li-Ion batteries prefers trickle charge or normal charging when it is used from 10% - 30%.
There are some myths about Li-ion batteries experiencing memory effect. This is not true. Over time, the practice of partial recharge or trickle charge, would "confuse" the charging and sensing system. As such, calibration to the sensing system would be needed or the charging meter would indicate a wrong battery status. This is sometimes known as the "digital" memory effect and does not affect the battery cells. To avoid this, it would be a good idea for a full-discharge after 30 charges to calibrate the battery meter.
Additional Note
1. http://en.wikipedia.org/wiki/Memory_effect
2. http://forum.notebookreview.com/showthread.php?t=91846
3. http://www.batteryuniversity.com/parttwo-34.htm
4. http://www.laptopbattery.net/laptopbattery_chemistry.html