While you are in school or working at office, using a pc with no internet would make you lose interest in everything because a PC with internet is like a Television set without Cable connection and you cannot just continue, but there is no other option because most of the websites are blocked by your employer in order to make sure you work more and surf less. But in this case free proxy servers would help you in gaining access to these blocked websites.
While accessing the web using a free proxy website you need to make sure you never login to any secured website, or make any purchases because when i recently checked out the cookies setup on a proxy website files it had the complete browsing history saved, which means that all your important data can be used by someone else in wrong means and you can lose your privacy. You can also lose your important email accounts or financial data while using a proxy website with logins, so you need to avoid these steps.
Another option is using Proxy Avoidance Software like Crossloop where in the server is hosted by your PC and no other 3rd party website where you have no fear of privacy problem or financial data loss. You will need to stay connected to the internet from your home in order to use these softwares because you can access the server setup at your home from any blocked connection at office/school and get a secured proxy connection.