I am assuming that you have the basics down -- a place and a time to rehearse.
I am also assuming that your group has a leader or someone who drives the artistic side of the group. If not, that is everyone in the band is a equal participant, my recommendation would be to designate a rehearsal leader for each rehearsal -- they do not need to DO everything or make every decision, but it is easier for a single person to coordinate the preparation and then enforce the guidelines you decide on for the rehearsal.
Physical Preparation items. The following is a list of items that it would be a good idea to get to your band members before a rehearsal. I know in many cases, many of the items on the list do not exist, but you need to make your best effort to see that they have as many as possible
- Sheet music/Arrangements (Some sort of notation)
- Even in Nashville, you can give some one a number chart.
- Either of your performances (if it is a new member), or a recording close to the version you do. If this is a songwriter with a batch of brand new tunes, the best demo you can get them, even if is just you with a guitar.
- Verbal descriptions
- Not the best choice, but it's better than nothing
- General Set list
- What does the group usually play.
- Rehearsal schedule
- When are you rehearsing (as many as needed, and as far ahead as possible)
- Rehearsal agenda
- For rehearsal X what are you planning on rehearsing.
This is also the time to solicit input from the other band members as far as what they don't feel comfortable with,what they feel they need work on,etc.