The most important thing you can do to prevent someone taking over your accounts is to use a strong password.
What is a strong password?
- A strong password will have no dictionary words or common names involved.
- The password will use a combination of upper and lower case letters, numbers and unusual characters!
- The longer the password the stronger it will be.
While something like disney62 is an example of a terribly weak password.
An on-line tool that checks how strong a password is suggests that disney62 can be cracked in approximately 24 hours.
You can check how strong a password similar to yours is using this on-line tool:
https://passfault.appspot.com/ (You don't need to enter your current passwords just enter similar passwords to get an idea)
If your password is weak update it in all instances now!!
Its also a good idea to use a different password for every website, particularly your on-line banking and email passwords should be different to the password you use for on-line purchases etc.
To keep track of your passwords you can use a password management tool for example keepass: http://keepass.info/