Should I put heat on my hair frequently?

I'm thinking of leaving my hair healthy(no heat or product) for the summer and then when school starts I will start doing stuff with it, with heat...but I'm scared my hair will fall out/break more than ever. I've seen girls who put heat in there hair and it looks uber cute and then when there hair is all product free...it doesn't look so good and sometimes you can see there scalp because of the lack of hair.So what should I do to my hair to avoid this, I really want to style it with heat and product more often but I don't want to be bald.