Extra or "background" work can be a lot of fun, but it requires a few things:
1) Are you able to quietly entertain yourself for hours (sometimes there is a lot of sitting around and waiting).
2) Do you have a cell phone to readily check emails, phone calls and texts for updates on changes to shoot times or to find out about new opportunities?
3) Are you physically able to work 12+ hours on long shooting days? What about night shoots that can last all night?
4) Do you have/or are you willing to upgrade your wardrobe to fit in requirements of shooting details.
5) Can you be on time? Are you punctual? Willing to take advice? Follow directions?
6) Must have a car or reliable transportation (not transit as a lot of shows start filming early in locations not reachable by transit).
As long as you can manage these important things... being an Extra is a ton of fun and great way to make extra cash. Its also a great way to see if the entertainment industry is right for you.