Blessing to you babyblue.
Here are a few suggestion I would like to share with you that worked for me. I started a community based group about 4 years ago. We are still going and growing.
1. I am just going to asume you have already done this but just in case some others read this, Im going to put it in anyway.
You have to know WHY you are starting a group. Are you called to start a group or are you just branching out on your own.? Its a great responsibility because you will, in fact be leading the people in your group in ministry similarly to that of a Pastor. You will be responsibile for the proper use of their gifts. And, you will be responsible the spiritual and musical growth of each member you cover. So you really should be sure that God has called you to found a music ministry on your own.
Assuming you have that in order.
2. You need to get a spiritual covering for your ministry. You should have some one to interceed on behalf of your ministry, someone to pray with and pray for you. And someone to deposit into YOU as well as your members, who understands music as a ministry.
3. Alot of times its good to start with the band since that may be the skeleton of your ministry. They will be what you build around. Start realistic and get the best you can get with what you have available.
As a personal note, I always tell people "dont get anyone who does play as well as you do on any particular instrument" if you play keys, get a keys player who is more polished than you. If you play bass, drums, cowbells, triangle, whatever... Get someone who's skills are atleast slightly more advanced than yours. Trust me, you will understand why when you get going. There is nothing wrong with having someone who is just learning to play come and join your ministry. But can you really build a ministry with solely that? I wouldnt.
4 Vocalists are all over the world. they will be easy to find. The problem will be finding those who understand the difference between singing and ministring. Thats going to be your job to discern that.
Colleges, postings in Craigslist and papers like that, word of mouth. Those will be the starting points to finding members.
5. Have a purpose for your ministry. Have a vision for your ministry AND ( here is where many people go wrong) have a PLAN on how to reach the vision. Write ALL these things down and have biblical references for them. Be prepared to share and explain them to your members.
6. One other thing to think on would ben your songs. Are you doing cover tunes, or are you going to have original material. Focus on CONTENT over fluff.
Of course, these are just opinions of DCWEATS on what I did to make my group grow.
Hope you take something helpful from it.