Start by ordering and reviewing your free credit report at www.annualcreditreport.com. Then put a credit alert, or even better, a credit freeze on your credit to prevent anyone from opening any accounts in your name.
Any of the 3 major credit reporting agencies can do this, Experian, Transunion or Equifax. Fraud alerts are supposed to alert you when someone applies for credit in your name, and they signal creditors to contact you for permission to issue credit in your name. Residents of any state can put a fraud alert on their reports. Creditors, however, aren't required to abide by or even check the alert.
A credit freeze goes a step further. With a credit freeze, no one can open any form of credit in your name. Your credit file is off limits to potential lenders, insurers and even potential employers.
Disclaimer: Please note that this answer does not constitute legal advice, and should not be relied on, since each state has different laws, each situation is fact specific, and it is impossible to evaluate a legal problem without a comprehensive consultation and review of all the facts and documents at issue. This answer does not create an attorney-client relationship.