If you have been a victim of identity theft, financial fraud, or think you might be a target, immediately contact the credit reporting agencies, freeze your accounts, and put fraud alerts on them. This will block most attacks. (You can also do this proactively to prevent identity theft.)
Open accounts at Experian, Transunion, and Equifax. Then put a freeze on each account. This makes it harder for anyone to get info from the account. Usually, you have to ok it (or unfreeze the account briefly.) Then, put a fraud alert on any on the three accounts. It will automatically be sent to the other two agencies and signifies that lenders / credit cards should take extra steps to ensure the identity of the person requesting the credit or money.
The freezes have to be done individually at each agency. Fraud alerts are shared and only need to be done at one agency. All of these services are free. They all also have enhanced monitoring services for $5-10 a month.
And of course, any financial accounts should have unique passwords and use 2FA. Not doing so is asking for problems.