First of all, you should consider installing the following software.
MBAM (Malwarebytes)
Emsisoft Emergency Kit.
Hitman Pro (not free, but you can use it only for scanning).
Those are on-demand scanners.
And now, if you're willing to buy, you can buy
Emsisoft or
ESET. If not, you should install a real antivirus like
360 Total Security or
Avast Free Antivirus.
Install
Chrome.
Use
PrivacyBadger.
With
HTTPSEverywhere.
Also with
uBlock.
With
Lastpass.
And
Click&Clean.
For a good measure, you can add
Privatefirewall.
For prevention & cleaning, add...
Adwcleaner.
Roguekiller.
Malwarebytes Anti-Exploit.
If you can, buy
Rollback RX.
But if you install everything except Rollback RX, then you're good to go.
Make sure to install only
one antivirus at one time. Only Avast, Emsisoft, 360 and ESET are antiviruses here. Everything else is not necessary but highly recommended. They can be, and should be, ran together.