For starters, re-enable the default Windows 8 security;
- Windows Defender
- Windows Smartscreen
- Windows Firewall
- UAC on default
- Windows Update to automatic
http://windows.microsoft.com/en-gb/windows-8/security-checklist-windows
http://www.microsoft.com/en-GB/security/pc-security/windows8.aspx
Work on from there, deciding what security works best for you.
Just to mention it, Smartscreen will often blocks the execution of known Antimalware tools like AdwCleaner, JRT, RogueKiller, etc. You can still safely execute them. It's good to leave Smartscreen enabled on your system, just saying that it have some "false detections" too sometimes.