Discharge
Fully discharge a battery before charging it. Discharging is the act of removing all the stored energy in the cells. Some battery chargers offer a discharge setting; however, some drivers hook up a series of lights to the cells, allowing them to discharge slowly. Whenever storing a battery pack, make sure it's fully discharged.
Peak Charging
Charge your cells at a consistent rate (i.e. 3.5 amps) and use a peak charger. Peak chargers are generally more expensive than timer chargers, but they prevent overheating and overcharging by monitoring the battery's peaking capacity, instead of merely timing the length of the charge.
Maintenance
To ensure peak performance from your packs, it's important to use the battery only once a day. Also, remember to wait for a heated battery to cool down before recharging it, and try to run it through a full charge-discharge cycle at least once a week.