Finding rehearsal and performance space
Before you actually launch your orchestra, you need to find a place for it to rehearse and a place for it to perform. You should have this settled well before you begin rehearsing. Before you can reasonably ask musicians to commit to playing, you need to be able to tell them exactly where you will be rehearsing and performing; location matters, especially if people have to drive long distances through heavy traffic after work in order to get to rehearsal on time. You also need to tell them exactly when you will be rehearsing and performing before asking them to commit, but that's a topic for another page.
An ideal rehearsal space should have chairs, music stands, and percussion equipment available for you to use, as well as good acoustics and enough space for a full orchestra. It's hard to find an ideal rehearsal space. Try your local high school and middle school band rooms, college music departments, large churches, community centers, and civic arts centers (if you're lucky enough to have one of those).
If you can't find a place that has music stands and percussion equipment available, you might have to ask your musicians to provide this equipment themselves, but this is quite burdensome, especially for the percussionists. No one enjoys hauling timpani. In the long term, you could purchase percussion equipment for the orchestra, but even if you could afford it (which would be something to try to get a grant for), you would still have to have a place to store it.
You might be able to use your rehearsal space for free, or you might have to pay a fee. This should be a very important part of your budget considerations. You might also have to reserve the space well in advance if there are many school and community groups sharing it, so this should be a very important part of your scheduling considerations. Fair warning: Some places might require that your group have liability insurance
Both the Redlands Community Orchestra and the Dexter Community Orchestra rehearse in their respective local high school band rooms. For Dexter, we had to send a representative to an annual scheduling meeting with the school district in which community groups had to bid for rehearsal and concert time slots. The RCO rehearses in the Redlands High School band room with no extra fuss because our conductor is the band director and has his own key. It's a California-style school where all the classrooms open to the outside, so the school doesn't have to worry about strange people wandering the hallways where they don't belong or send a custodian out to unlock and monitor the building, and there are no other groups using the space.
The same equipment, funding, and scheduling considerations apply for the place where you will perform your concerts. Try your local high school auditoriums, college auditoriums, large churches, your civic auditorium (if you're lucky enough to have one), and any other theaters or auditoriums in your town. Keep in mind that if your performance venue doesn't have percussion equipment and music stands, you will have to either ask your musicians to provide them, or you will have to haul them from your rehearsal space, and your rehearsal venue will have to be willing to let you do this. This is made easier if you're rehearsing and performing on the same campus.