Massage your scalp. Not only is it relaxing, but it stimulates blood flow to your scalp
You can add an oil like coconut or olive for an extra boost of nutrients to your hair.
Cut heat styling, which you mentioned; try to protect your hair from breakage, which someone else already mentioned; drink plenty of water; eat a nutritious, balanced diet; up your protein intake; get enough sleep; keep your stress levels down; try supplements like biotin. That's all I can think of for now