If you are looking for advice on how to keep your system running optimally, please review the next few tips.
While there is a lot of advice out on the internet about what to do, please realize much of it isn't actually something you should do. While we could offer our advice, there are plenty of people offering tips which we fully endorse.
https://decentsecurity.com offers some of the best tips and advice you can find if you don't know where to start. Don't use registry cleaners, enable UAC, and what to do every quarter to keep your system running. We highly recommend you review what they have.
https://www.privacytools.io/ offers a lot of resources to keep you secure online.
There are a lot of people that will tell you to defragment your computer, to clean your registry, and all kinds of other things to do in order to speed up your PC. I personally have not recommended any defragmentation tools outside of those which are built into the OS, and are already running for you. https://decentsecurity.com will tell you about registry cleaners and http://www.hofmannc.de/en/windows-7-defragmenter-test/ has information on defragmentation.