There are many facets in preparing for rehearsals. Most of them are covered in the ensuing chapters. It is important to discuss what rehearsal means. If we agree that the work in one phase of production is your preparation for the next phase then getting ready for rehearsal includes everything listed in those chapters plus a few intangibles such as tone and purpose.
To provide people with the environment where they can do their best work requires sensitivity of measurable proportions. Knowing when and how to insert oneself requires amazing sensitivity to the work being done in the rehearsal hall. We want assistant stage managers to be quick and invisible. We want lines loudly and quickly announced. We want breaks to not upset the work being done but not be ignored. In short we want a bit of everything from a stage manager but in such a way you hardly know they are there.
Here are a few suggestions you should include in your preparations for first rehearsal:
PHYSICAL - what are the physical limitations of the rehearsal hall? Do you have mirrors? If you are doing a dance show do you have adequate space for all the paraphernalia that comes with dancers? (Dance bags with shoes and outfits.) It may sound funny but when you have a dance core of 64, a chorus of 40, and assorted principals and other performers you need a lot of space just for their stuff. Where does the director want to focus their attention in the rehearsal room? Where is the piano and drums? and on and on. I prefer to put my SM table between the entrance and the director - wherever that may be - and put the piano and the drummer on the opposite of the director. That way I have direct access to the director, I can control who comes in and out of the room, and the director has direct access to the piano and the rest of the artistic team.
EMOTIONAL - Since you, the director, and the actors are all going to be spending a lot of time together make sure the 'tone' of the room is conducive to the work being done. On large productions you want to make sure you set a disciplined working tone - being careful to keep the noise level to a minimum - while on smaller productions it may be entirely possible to have a much looser hold on the space.
ORGANIZATIONAL - while it is probably not necessary to have a sign in sheet for a four person play it is for a forty person production. Place the sign in sheet in a place convenient to the stage manager and remind actors to sign in as they enter. This way a few minutes before each rehearsal you can quickly check who has arrived and who hasn't and keep an eye out for those late stragglers coming in the door.
It is a professional expectation that actors, singers, and dancers show up prepared for work. At the appointed hour you are expected to be ready to launch into rehearsal and not take the time to get ready to rehearse. Most people will start showing up long before the rehearsals are set to begin, especially if they are trying to warm up their bodies. There is an unwritten stage management rule that a stage manager is there one hour prior to every rehearsal and one half hour after rehearsal. This allows proper preparation for the stage management team as well as the artists and allows ample time for the stage manager and the director to spend time either in preparation or in conclusion of a days worth of work.