The first thing you can do to get started to go get a professional headshot. Just get a few shots, one or two looks from your chest up. You can get started by looking at craigslist.com under film/tv or talent gigs. There is also Mandy.com where people will cast indie films. I did most of my beginning work as an actor in student films. Student films are a great way to build a small resume.
Take any part that is offered, no matter how small. Once you are on set, talk and learn from the other actors and the director.
I hope that helps.
Keelen