Always charge your battery properly. know the time it take to charge, A 1500 mAh battery on a 250mAh charger will need to charge 6 hours. Make sure your battery is flat first, Don't guess as it could be a costly one. Over charging will damage the battery. A Smart charger will stop charging or go into trickle charge mode when the battery is full.
Lipo batteries need to be handled with care, do not break the packaging or over charge. Using the battery till its flat will damage it and it may not charge again. Always use a lipo alarm, this will sound when you have to stop using the lipo battery.