To make your hair softer first when you condition in the shower leave it in and bathe the rest of your body then rinse it out.
Next you should wait until you hair is 50ish percent dry so the heat won't have to be in contact with your hair as long.
You should also have days where you don't curl of straighten your hair. This will decrease the amount of damage done to your hair. When you do straighten or curl your hair use a heat protectant.