A lot of it is luck. I've been building my audio post business for about four years now and it's been a tough go. It took me quite while of "paying my dues" but I worked my way up the ladder in the music biz to become musical director for and play with an internationally known oldies group at venues like Carnagie Hall, the Apollo Theatre, indoor arenas and outdoor festivals with tens of thousands in the audience. During my career as a musician I was fortunate enough to meet many "big" names and converse with them. I had a very nice career because I actually listened to lots good advice. If you have talent and follow the basic rules of personal behavior and professionalism you can do well. Here's what I've gleaned over the years:
Be positive
Work hard
Be professional
Work hard
Be punctual
Work hard
Be prepared
Work hard
Ask questions
Work hard
Keep business and personal separate
Work hard
Keep your tickle file active
Work hard
Keep up with the bread and butter communication (phone calls, e-mails, etc. to say thanks, great to work with you, here's what I'm working on now, got any work for me and the like)
Work hard
Keep it legal (contracts, etc.) [If they won't sign a contract proceed with extreme caution]
Work hard
Maintain your health (exercise, good food, sleep)
Work hard
"You can spend your time, health and money on alcohol, drugs, bimbos and partying, or you can spend your time, health and money on your career" (Tina Weymouth - Bassist with Talking Heads)
Work hard
Never burn bridges (today’s asshole is tomorrows producer)
Work hard
Never stop learning
Work hard
Always listen to and try to respect other points of view
Work hard
Work hard
Work hard
"Life has been made for you to enjoy, but you won't enjoy it unless you pay for it with some good, hard work. This is one price that will never be marked down." - Harpo Marx