While I do not believe there is such thing as being “completely secure” on the Internet there are many best practices which can make you safer.
- Never use the same password for more than one website, etc.
- Never use an easily guessed password.
- Use 2-Factor authentication wherever possible.
I’m including a link which goes over the top passwords of 2015. As it states, if you find one of yours in this list it’s time to change it.