The emphasis should be on the work you do. The value you give to others.
If you haven't done the work, why should anyone care?
Opportunity will arise when you show you can continually work to a quality higher than others.
The people who will hire you, cast you, sign you, are the people who know you and your work. They're people who know you.
Sometimes you need to reach out, send a letter, make a phone call, but the priority is the work. The art.
Because you're in this to make art, right? To give someone the feelings films gave you when you were a kid.
Social networking is a great tool, but harass people too soon and they'll hate you forever. Exhaust the Hollywood contact too soon and you'll be seen as an amateur.
Do the work. Be better at it than the others. There are no excuses anymore, no barriers; the technology is in our hands. Stay away from Starbucks for a week and use the money to rent a good camera. Stay off Facebook for a week and use the time to write your dream project.
You'll be discovered when you're amazing. People don't care for talent. Nearly everyone has talent, they just never nurture it, never drive the car far enough. Be so good at what you do that nobody can deny you.