What should I do to preserve the enamel?

do not combine cold and hot food
, do not eat ice cream, wait until it thaws a little.
sometimes use a paste for sensitive teeth
What should I do if my teeth are already reacting to the cold?

Plus to all of the above:

eating foods rich in calcium and fluoride
should be shown to the dentist if the pain after contact with cold does not go away for a long time,
to strengthen the enamel. For example, fluoridation.
And definitely:

do not forget to visit the dentist regularly!
Take care of your teeth!