Luckily today it's not hard to secure your credit information. As long as you're not looking to take a loan any time soon, your first step should be to "freeze" your credit report. That way no one can open an account without getting permission from you to look at your credit history.
Once that's in place, you'll need to change some habits when handling key financial information. Here's some simple steps you can take:
Shred financial documents and paperwork that have any personal information before you throw them out. this includes all statements that have your account number or Social Security number on them. If you commonly write account numbers on checks when you pay bills, be sure to shred those too when you no longer need them.