In this day and age of non-stop data breaches and the fact that your data is being bought and sold all over the planet, the most sure fire way to protect your credit it to freeze your credit.
In the US that means contacting Equifax, Experian and Transunion. Back when I froze my credit, this would cost you money to freeze and unfreeze your credit. The good news is, as of September 2018, a new federal law allows people to freeze and unfreeze their credit at the big 3 credit bureaus for free.
Frankly it’s disgusting that the credit bureaus were making money from data breaches, some of their own making. See Equifax breach.
For information on credit freezing see the FTC’s FAQ.
Freezing your credit is sort of like a firewall for your credit that only you can open and close as needed.
The other thing I noticed on the FTC site is a mechanism for opting out of the non-stop prescreened credit offers that we all receive. You will have to provide your SSN and date of birth, but given that data has probably already been compromised/sold, shouldn’t be that big of a deal and it stops a little bit of junk mail.
Update 8/7/19: Given the rash of breaches in 2019 so far, it’s even more important that people freeze their credit. It’s pretty much the only solution at this point.