The brown leaf edges are a generic symptom without one specific cause. It could be heat damage, but more likely it is improper watering. As Christine has pointed out, without knowing how yours is potted, it is hard to give specific watering instructions. If it is properly potted and close to a sunny window, then it would need a thorough watering as soon as the surface of the soil is dry. If it is in a large pot or away from the window, then allow the top inch of soil to dry between waterings. Try to protect it from temps above 85 degrees and hot sun shining directly on the leaves.
