Brown edges can be caused by too much salt build up in the soil and also from flouride in tap water. Using distilled water might help but also be sure that when you water, give the plant enough water so that it saturates the soil and runs out the drain holes. Never let a plant sit in a tray of water for very long or you will end up with root rot.
Dry, brown leaf edges can caused by too little humidity; misting helps but sometimes it's not enough especially during winter when folks have the heat on which can dry plants out pretty quickly. You can place the plant on a tray of moist pebbles which raises the humidity around the plant, adding a wee bit of water to the pebble tray as it evaporates.
