Twelve million Americans become a victim of identity theft each year. Fortunately, you do not have to be one of them. You should never use a public Wi-Fi network to make a financial transaction. A hacker could very easily access your username, password and account number if you use a public Wi-Fi network.
You also want to make sure that you avoid posting a picture of your debit or credit card online. That might seem like a given, but it is something that many people do anyway. If you post a picture of your credit or debit card, then you are asking for someone to steal the number off of it.
When you are setting passwords, you should make them long. You should also make sure that you use several different characters and avoid using a password that people could very easily figure out, such as 1234567. Additionally, you should make sure that you change your password often.
Source: The Stupidest Things You're Doing to Put Your Identity at Risk