Depending on the type of battery, different techniques are required. If you really want to understand what is best, read the following:
http://www.rcbatteryclinic.com
http://www.camlight.com/techinfo/techtips.html
http://www.whenshtf.com/showthread.php?t=2153
http://www.srbatteries.com/nimh.htm
http://dansdata.com/gz011.htm
http://users.frii.com/dlc/battery.htm
These sites are all quite good and will point you in the right direction for proper battery care.