Finding a conductor
The very first thing you should do (after deciding very broadly your orchestra's goals) is to find a conductor. There is no point in recruiting musicians until you know you will have someone to conduct the group. I you are going to be the conductor, then you might want to find a couple of co-organizers to help you out because taking on both the musical and the organizational leadership of the orchestra is probably going to be too large of a task for you in the long run, especially if you also have a day job.
Your conductor/music director (I'm using these terms interchangeably) will lead rehearsals and concerts be responsible for all the group's musical decisions, such as deciding what music to play. The conductor need not have extensive managerial duties, but he/she should be involved in decisions about the group's musical vision and goals, scheduling concerts and rehearsals, auditions and audition policies, and anything else that affects the musical product.
Your conductor needs to be highly skilled in both conducting orchestral music and in leading amateur musicians. Musical skill is an obvious necessity, but so too is a positive, encouraging, confidence-inspiring manner on the podium. You want a conductor who can coax out the best musical results from your musicians without making them feel inadequate. You don't want someone who yells at your musicians; it's supposed to be fun. Be aware that a top-notch conductor who has only worked with professionals may have unrealistic expectations for the group and may not work well with amateurs. Also be aware that a conductor who works exclusively with amateurs, such as a school band director, may not have as much musical skill as you would like.
When searching for a conductor, consider local school band/orchestra directors, students or faculty from a local music school, conductors of church orchestras or other groups, and anyone else you can think of. You could reach out to existing groups and ask if any of their members are interested in conducting a new group or can refer you to anyone who would be.
Before settling on a conductor, do your homework. Find out what other people think of his/her conducting skill and manner. If he/she is a school band director, talk to some band parents or former band students to see what they think. See if you can watch a concert or sit in on a rehearsal he/she is leading.
Make sure that you and your conductor share the same vision and goals for the orchestra from the start. Talk through all your ideas at the very beginning, make compromises where necessary, and be clear on what you expect from each other. You're essentially going to be business partners, and you don't want any unpleasant surprises or misunderdandings later.
Will you pay your conductor? If so, how much does your conductor want to be paid, and how much can you afford to pay (and where is this money coming from)? Will you pay your conductor per service (rehearsal or concert), per concert cycle, or per season? Even if your conductor is volunteering, it's still nice for the orchestra to show its appreciation at the end of the concert or the end of the season in some way. After its first season, the RCO quietly took a voluntary collection of funds from musicians and purchased a special gift for our much-loved conductor (a high school band and orchestra director), who very graciously volunteered his time and efforts to our group for the first few seasons.
Designate an assistant conductor
What happens if your conductor gets the flu and has to miss a rehearsal or has a car accident the day before a concert? It can happen, and your group should be prepared. You can still rehearse or perform if pretty much anyone else is missing, but you HAVE to have a conductor. Designate an assistant conductor or at least have in mind a list of substitutes you can call in case of an emergency.