1. Delete files you download and save and then empty the recycle bin. Otherwise, the next person to use the computer has access to your files.
2. Use your browser's private mode. This will keep cookies from tracking you, and make it so no passwords are remembered -- all at once! Every browser comes with one. In Firefox, it's called "New Private Window"; in Chrome, it's called "New Incognito Window"; in Edge, it's "New InPrivate Window." Search for the option by pulling up the browser and selecting the options icon (sometimes three dots and sometimes three bars). When in private mode, your browser may look a little different to let you know you aren't being tracked. You have to choose it every time you open a browser.
3. If you don't use the private browsing mode, make sure to log out completely of whatever accounts you've logged into. This goes for email and social media accounts. The next person may be able to access your accounts if you don't. If you use private browsing modes, there is no reason to log out, because once the browser is closed, you are logged out of all accounts. Plus, it's rude to not log out for the next person. If they are needing their account on the same service, they will have to logout for you.
4. If you don't use the private browsing mode, delete cookies and search history. Private browsing does this for you automatically when you close the browser. Otherwise, it's very easy for the next person to see all the sites you visited.
5. Use USBs as a last resort on public computers. It's too easy to forget them in the computer itself, compromising your files and property. Email the files to yourself instead and be able to access from any computer!