I got my start through a friend with whom I had worked in restaurants. He had landed a job as a personal assistant to a very, VERY wealthy gentleman who was also seeking a private chef. I worked for this wonderful man for six years, until he died very suddenly.
After his death, I was unemployed for 13 months. It took every ounce of resourcefulness for me to construct a new job for myself. I contacted everyone I knew and asked them to contact everyone THEY knew. I submitted a very professional portfolio to all the private chef agencies (and got NO leads from them) and posted ads on craigslist. Finally, I landed a job working for a couple who owned a mortgage business. I was happily employed with them until the bottom fell out of the housing industry. I was laid off, along with all their other domestic help and most of their mortgage company employees. For awhile, they even had their house on the market.
I was unemployed for eight months and finally HAD to take a job back in the kitchen. It is a very difficult time to break into private chef work - according to all the agencies I deal with. Unless you are truly lucky and land a job working for someone too wealthy to be affected by the economy, it may be a long time before you find something steady that pays well. I got a call last week about working part time for a family but when I told them my rates, they never called back.
In summation, my experience has been that finding a successful position comes mainly through who you know. Good luck!