You exchange the relationship from boss to customer and business partner. You divide your customer facing work unto three categories: DELIVERY, MANAGEMENT, STEERING
The relationship must be strong and you must have a working relationship, can never be caustic. Make sure that you are making the customer shine, always. Be a trusted advisor when you can. Say yes a lot, but setting expectations and saying no is also okay and important.
Risk tolerance and thick skin is key. The financial reward is sky high.
One man army, taking projects in megacorps. I answer to no one.