How do i stop cheating Google AdSense?

I got this message from them:

Hello Soumen Bose,

It has come to our attention that invalid clicks or impressions have been generated on the Google ads on your site(s) through users of third-party programmes paid or provided with other incentives to visit your site. Such programmes may include, but are not limited to auto-surf, pay-to-surf, pay-to-read or pay-to-click sites. As a reminder, any method of generating invalid clicks or impressions is strictly prohibited by our Terms %26 Conditions and programme policies: https://www.google.com/adsense/localized... https://www.google.com/adsense/policies?... If we continue to detect invalid clicks or impressions from these services on your ads, we may disable your account to protect our advertisers. Yours sincerely, The Google AdSense Team

Now, i did sign up at places for free traffic, can u please tell me sites that violate google terms %26 policies?

I dont have money to spend on softwares, still then ...

How do i stop cheating Google AdSense?free antivirus download

The sites you used to get free traffic is an example of site that can lead to your violation of Adsense TOS. They sent you a warning after you used the site, so that as well as other auto-surf, pay-to-surf, pay-to-read or pay-to-click sites are against the rules. Any site that promises you free traffic or those "100,000 visits for only $29.99" are low quality traffic that can get in you big trouble with Adsense.