A lot of things can happen online, some of which are beyond your control. One of these is invalid click activities that are caused by a number of things, but can lead you into one unfortunate situation - getting banned from AdSense for good. Since you need AdSense to keep track of your website's performance, you should do anything possible to protect yourself against invalid clicks.
StatCounter can help you in this mission. This is a web traffic analysis tool that lets you track all clicks and exit links. Through it, you will know where a majority of your invalid clicks are coming from, and the corresponding IPs that you can then block to protect your AdSense account.
Getting started is as easy as signing up and creating an account. You can then create a new project for a website that you want to track. Like most analytics tools, StatCounter is fairly easy to use. Make sure to select a counter or Invisible tracking, and opt to receive reports in a weekly or monthly basis, so that you can keep an eye on invalid AdSense clicks.
After entering the appropriate information, press the "Add Project" button which will take you to the "Choose an installation Guide for your website" page - here click the "Default Installation Guide" link. Now, StatCounter will give you a code along with instructions on how to install this code on your website. After adding the code, press the "Check Installation" button on the right toward the bottom of the page in order to finish the installation process.