(adsbygoogle = window.adsbygoogle || []).push({}); So, one common happening is when you use anything PHP, you will get all cloudflare IPs. Then can be very annoying if you are trying to ban users or log important things.
Use this simple code in your script to eliminate that problem:

    

if (isset($_SERVER["HTTP_CF_CONNECTING_IP"])) {

  $_SERVER['REMOTE_ADDR'] = $_SERVER["HTTP_CF_CONNECTING_IP"];

}

This is not fullproof and can be bypassed!
Hope this is beneficial to some of you new guys out there!
For those using Wordpress or another type of CMS/system.. Check out their plugins. Usually someone has made a plugin to convert the IPs and doing so properly with the way the CMS is built.

Can be exploited, by setting the headers manually (Example if they have your server ip they can bypass CloudFlare).

Never thought of that. Thanks for letting me know!