@bingvarstand: Use common sense
a) Make sure you have the latest Windows OS System and make sure it's fully up-to-date via Windows Update.
b) Make sure you have the latest version of Avast.
c) Only download programs software from official website.
d) Make sure all your other browsers (google chrome, Firefox, internet explorer are up-to-date) and other program such as java, flash player, adobe reader. Including your graphics drivers. Including your other programs that you use i.e. other editing program such as AutoCAD and etc are fully up-to-date.
e) Install a second anti malware scanner such as MalwareBytes.
f) Don't click on links/ads that is too good to be true that appear in the browser. Install AdBlock Plus to block these annoying messages.
g) Don't click on links/attachment in emails from unknown senders. If a friend or a company sends a attachment or links that you are not sure about contact them to make sure.
h) Install Unchecky so whenever you install a program it won't install potential unwanted software/program along with the program you want to install, because at present when you want to install a program, it also installs other programs that is not necessary.
i) Scan your whole computer once every week by Avast and MalwareBytes.
j) Don't install other optimizer/system registry/ etc because they will cause more harm in your computer.
k) Make sure you install patches/updates/bug fixes/etc that is delivered through your machine manufacturer i.e. HP, DELL, and etc. They use HP Support Assistant and DELL Support Assist to transfer these updates to your computer.