Gathering a Core Group

Since Shannon and I have resolved that, as far as we know, we are planning to plant a church, I would love some wisdom from others. How would you go about establishing a core group of people for the church plant? What things would you stress during the time of meeting before the new church "launches" publicly? What would you determine as the primary reasons for choosing a particular place to plant? I ask all of these questions, and there are plenty more, because I truly want to hear from others. I'm looking forward to hearing your thoughts.