This is general information, not personalized advice about your specific situation — if you've already experienced fraud or identity theft, consider reaching out to the bureaus and your financial institutions directly. For everyone else, the strongest everyday protection is one most people have never used: a credit freeze.
Credit freeze
Locks your credit report so that lenders can't access it — which means new accounts generally can't be opened in your name, even by someone with your Social Security number. It's free, it doesn't affect your credit score, and you can lift it temporarily whenever you actually need to apply for credit.
Fraud alert
A lighter-weight option: it doesn't block new accounts outright, but requires lenders to take extra steps to verify your identity before opening one. Easier to set up (often through just one bureau, which then notifies the others) but a weaker barrier than a freeze.
Why a freeze over paid monitoring
Paid credit monitoring services can alert you after something has already happened, like a new account being opened. A freeze is generally considered more effective for actually preventing that new account from being opened in the first place, and it costs nothing. Monitoring can still be useful as a complement, but it isn't a substitute for a freeze.
See Tracking Your Credit for how to pull your free report and score in the first place.