Do's:
Properly "condition" (fully charge/discharge for first 3 cycles) the battery when it is new.
Keep the battery and the contact terminals clean.
Avoid exposing the battery to extreme heat and cold.
Use the battery. If possible, avoid letting your battery sit dormant for long periods of time.
Use only the phone options and accessories that you really need.
Charge and re-condition a battery after an extended idle period.

Don'ts:

Toss, drop, or otherwise abuse the battery.
Short-circuit the battery.
Open and expose the cell contents.
Modify the battery casing and/or housing.
Allow the battery to be exposed to rain or excessive moisture.
Incinerate a battery. Properly dispose of a used battery.