Search for opportunities online. This is the digital age and one of the easiest ways to find information is on the Internet. Classified ad sites like Craigslist or FilmStaff often have dedicated film, television or video job sections. Independent, student or low budget productions post want ads on these sites. You may not make the big bucks, but these smaller productions are a great way to make connections within the industry.
Browse television and film trade publications. Bigger budget productions will sometimes advertise in industry-related publications, such as "Variety" or the "Hollywood Reporter". It's a good idea to subscribe to a few of these magazines and newspapers to find out what's going on in the business and to seek out opportunities.
Contact your regional film commission. Many cities have film offices or organizations that help coordinate productions. Contact your local film commission and check its website. Chances are if a production is starting up in your area, the film office will know about it and may be able to help you find a position on set. Also, consider volunteering at the film office. It's another great way to make connections.
Call local colleges and universities. Many students produce short and feature films for classes, clubs or other organizations and don't have access to the same resources that professional productions do, so they're always looking for people to help on set, whether it be as an extra or somebody to hold the boom mic. Check in with film professors or film clubs on campus to see if students require any help. You may not be paid (or paid very little) but the experience will be valuable and it's something you can put on a resume.