If you MUST use SM
Use a pseudonym.
Use a unique email address.
Use a unique password.
Use a unique PAYG unregisterd SIM (not possible in all countries) if you think you MUST give them a phone number. Better to regard the account as disposable and ignore 2FA. Use a decent unique password.
Do not ever post your real age or address or real names of any family or friends. Use email with people that need to know that stuff.
The Advertisers are the customers and you are the product. Do not use it for Customer Support, use your own website if you are commercial.