To generate your password those things will be used:
1 - Capital Letters (e.g. D, R, S)
2 - Lowercase Letters (e.g. d, r, s)
3 - Numbers (e.g. 3, 6)
4 - Symbols (e.g. !, ?, -)
Some suggestions for your passwords:
1 - Do not use the same password, security question and answer for multiple important accounts.
2 - Use a password that has at least 16 characters, use at least one number, one uppercase letter, one lowercase letter and one special symbol.
3 - Do not use the names of your families, friends or pets in your passwords.
4 - Do not use two or more similar passwords which most of their characters are same, for example, ilovefreshflowersMac, ilovefreshflowersDropBox, since if one of these passwords is stolen, then it means that all of these passwords are stolen.
5 - Do not log in to important accounts on the computers of others, or when connected to a public Wi-Fi hotspot, Tor, free VPN or web proxy.