Protect your personal sphere online with the appropriate settings. On almost all social media platforms you can adjust the settings to ensure that only your friends can read your posts and comments.
Make a choice: A large amount of followers and friends is great, but there is a danger that there might be people, who might have different intentions than you. Put the emphasis on quality instead of quantity.
Actively campaign against cyberbullying and build a network with your friends, that will stop cyberbullying in its tracks.
Remember: The same rules apply in the online world as in real life. The Internet is not a legal vacuum. Establish for yourself and others the same standards as you would apply in “normal” life