Virtual Private Networks
I suggest you always use a virtual private network a.k.a. a VPN. VPNs hide your actual IP from the websites you visit, thus the website does not know who you are. Most VPNs encrypt your traffic between the VPN and your computer. This allows you to go unnoticed by your network administrators and a VPN also prevents a man-in-middle attack that can compromise your passwords.
Always use different passwords for different sites. The issue is, if one site gets hacked your passwords could be compromised and some sites do not store their passwords correctly, thus making it very easy from the to see your actual password in plain text. This will allow the hacker to not just get into your account on that site, but will allow them to gain access to any account you use that uses the same password.
I recommend using a password vault to store your passwords in, this will allow you to remember all of them and the vault itself is encrypted so anyone who does not have the encryption key to your vault, cannot see your passwords.
Also make sure your passwords are strong, longer passwords are exponentially harder to crack than shorter passwords.
You should always make sure your connection is encrypted before you enter your login credentials. You can see if your connection is encrypted by looking for the padlock at the address bar.
When using public WiFi, make sure you always use a VPN to encrypt your traffic. It is not wise to login into any account without using a VPN on public WiFi. Without a VPN a person can easily just snatch your password if the site you are using doesn't support encryption. Even if the site supports encryption, it is still not wise to use it without a VPN.