What is the Most perfect ways to save the computer from Adware, Spyware and all the other virus attacks without paying anything?

i found avira antivirus best .....stay away from porn / torrent sites

Thank you all for the answers.

The solution worked for me is using USB Vaccine and adblocker. 

Vote it up if you find it useful.

My advice

1. Dont click on ads - especially Make money Ads / Meet her in your town Ads

2. On installing any wanted software read al the pages instead clicking next next next. Carefullycheck  the prompt where unwanted softwares are installed.

3. Install Avast Antivirus free- which give you best protection. If you refer20 person you will get internet security premium free. 

4. Never try junk softwares. Only go for necessary , genuine and trusted ones

1. Use good free antispam and antivirus software on your system. Example: Avast/AVG Antivirus
2. Review all the files before opening from external sources and identify which is trusted one. Example : USB/Email, etc

Use Software of Trusted Suppliers and minimize the use of Flash Drives