I just started to work with CSS Media Queries and found some helpful resources and snippets.
This article on CSS Tricks gives you Media Queries for standard devices.
After making my website fully fluid and added some Media Queries for different views of screens, my iPhone gave me a normal none mobile view of my project. So I searched for a solution and found one. The following snippet must me placed in your header so the pixel ratio can be set and your website is scalable for devices such as iPhone.
<meta name="viewport" content="width=device-width, initial-scale=1.0, user-scalable=yes">