Here are some great tips posted by Mark L. Chambers on dummies.com - Yes! I do find Dummies guides to be very easy to use and great for simply straight to-the-point tips.
Actually, the tips in the following list are worth following whether you’re a junior, a senior, a Mac user, or a PC person. The Internet is full of wondrous sites, but it’s also full of unsavory characters you need to guard against. Use the tips here as a guideline to things you should never do and use your own common sense as well.
Never enter personal information in an email message when you don’t know the recipient.
Never enter personal information on a website provided as a link in an email message.
Never include personal information in an Internet forum, discussion group, or newsgroup message.
Never use the same password for all your electronic business.
Never divulge personal information to others over an instant message connection.
Never use your MacBook on the road without turning on your El Capitan firewall.
Never buy from an online store that doesn’t offer a secure, encrypted connection when you’re prompted for your personal information and credit card number.
Never download a file from a site you don’t trust.
Never allow a stranger to connect to your Mac using the Screen Sharing feature.
Never allow children to use the Internet without guidance and supervision.
Stay tuned for more helpful tips on managing yourself easily and safely on the World Wide Web!