Older browsers have more security flaws.
Use your best judgment in giving out sensitive information. All the skills you use to decide whether to give out credit card or personal information in other areas of life are also your best defence on the Internet and should serve you well. Have a look at the very helpful Better Business Bureau's tips on cybershopping for the US and Canada. Configure your browser to tell you when you enter and leave a secure site. Review the security settings on your browser.