According to Huffington Post, these are the top 25 most common passwords:
123456
123456789
qwerty
12345678
111111
1234567890
1234567
password
123123
987654321
qwertyuiop
mynoob
123321
666666
18atcskd2w
7777777
1q2w3e4r
654321
555555
3rjs1la7qe
google
1q2w3e4r5t
123qwe
zxcvbnm
1q2w3e
...So obviously, if you use any of those, you need to change them.
I use an app on my phone called 1Password to hold on my passwords, so I don't get in the dangerous habit of using the same password for all my log-ins.
And you might want to try this site that generates passwords for you that are pretty much unguessable. You can set the number of characters and whether you want symbols in your password or not.
Check out passwordgenerator.net here.