When should I use responsive design?

Often when planning out a website, one must decide if responsive design is an appropriate approach for the project. There are many considerations to take an account before jumping the gun on this.

Lets start out with the limitations of fixed width designs:

1. The usability and interface don’t work on screens that are too small or to big.
2. Unreadable text on most mobile devices
3. Form functionality is often flawed
4. Nonessential information shown to mobile users

With these points in mind, one must decide if responsive design is an appropriate solution:

1. What is my target audience?
2. Does the website require a mobile interface?
3. Does my audience use mobile and tablet devices?
4. Is it okay to hide certain elements for the mobile version?
5. Am I okay with increased page load time when loading up extra CSS?
6. Is there budget for UX and Design for both the desktop and mobile platforms?
7. Should there be an intermediary tablet-optimized layout?
8. Can compromises be made with the design to allow for a consistent look across different interfaces.

Just some things to keep in mind.

For an extra read:

Why 2013 Is the Year of Responsive Web Design