Dry frizzy hair

so I origonally have curly hair, buti straighten it, but it ends up all dry and frizzy.
what are things I can do to my hair to make it look healthy and weighed down?
please be specific!!

There's treatment products you can buy to keep it moisterised. Ask your local chemist.

stop straightening it for a while... give it a few days to heal in between straightenings

There are frizz shampoos you could use.
And there are shops/hair salons that have shampoos right for your hair.
Also you can have it permantley straight at a salon but it'll get curly again after your hair grows out=)