Never reuse a password and remember to avoid using repeated characters, dictionary words, numeric sequences and personal information (date of birth, name of the street, pet's name etc) as your password. We would also recommend to change your password every 3 months. If you have troubles creating strong passwords and keeping track of them, there are several password managers that can help you with it.
Remember to never disclose your password to anyone, and avoid using it openly in a public place.