First of all blocking is not nearly as complicated as most stage managers try to make it. You are responsible for keeping track of the rough blocking of the play. When I say rough blocking I mean entrances and exits, where actors move and stand or sit, and where they pick up or put down props. In most cases, and unlike dance captains, whether they start on their left foot or not is not indicative of their character unless it alters the action of the play. So an actor who enters with a gun hidden in their upstage hand would be noted as such. A bunch of actors running on with spears would not require a specific hand to hold it in unless their is a specific reason to do so.
All stage managers at Penn State type their scripts into a word document so that they can manipulate the margins. For the blocking script I would manipulate the margins so that I had as much room in the left hand margin of the page and little on the right hand side (remember pagination! Even while you are manipulating the margins of your document make sure you maintain the page numbers that everyone else is using as well. You will be asked what page you are on in the rehearsal process. If your pages don't match everyone else it holds up the process of rehearsal and stage managers don't do that.)
On the back of the opposing page (in the left hand side of my binder) I reproduce a small copy of the floor plan of the play I am working on. If it is a multiple set show I have a floor plan for each scene that is in my production. In some cases it may require more than one floor plan if the blocking is very complicated and/or the cast size is large.
With most plays I keep 90% of the blocking in that left hand margin. Remember to write in pencil. It changes often in rehearsal. I use a small acrylic see through triangle that allows me to follow along with the script and stay on book while also providing the strait edge for me to draw in precisely where the move takes place. In addition, I have a consistent manner in which I notate blocking. Always WHO, then HOW, and then WHAT. So Aldonza in crossing to Sancho and sitting down would look something like Figure 1 below. To further aid in quickly identifying what is taking place, characters are always circled. So you will note that the circled A = Aldonza and the circled S=Sancho. This allows me to distinguish rapidly the WHO in the blocking. Next the HOW is denoted in the most simple manner possible; X=cross. I use a very simple notation system. P with an arrow pointing in a direction substitutes for Pick Up, Pull, Push, and Put Down. It gives you the HOW they do it. Finally, i follow it up with WHAT they do or do it to. With my notation you either Rise or Sit so an R with and arrow up means you get up from whatever position you are in. Likewise and S with an arrow down means you get down. K = kneel, etc. If they do it to something, say they SIT in the CHAIR. Chair is written out and underlined; Chair.
So Aldonza crossing to Sancho and sitting in the chair would look like:
A X S chair S; with the A & S circled and the final S with an arrow pointing down.
FIGURE 1
Quixote taking his spear and exiting in Left 1 would look like:
FIGURE 2
with Q being circled to indicate the character, 't' with an arrow to indicate 'take', and "spear" underlined and the direction to exit in left 1.
For more complicated blocking I refer to the pictures of ground plan on the left hand side of the page. I place a number to indicate which floorplan to tie the blocking to and then map it out on that particular floor plan.
By underlining props and sittables I can easily track through the show and compare lists of props, props tracking, etc so that my paperwork can be as complete as possible.
Once you have blocked the show it is a very good idea to include a blocking key in the front of your blocking book.
In large chorus shows I do provide a variation. If you look at a show like Annie, the principal characters (Annie, Warbucks, Lily, Ms. Hannigan, etc) can all be simple letters in circles. If you remember back to the auditions section, as a part of the definition of a chorus member is the language that they play more than one character through the play*. In the cases where they play multiple characters or if they are just the "dancing or singing chorus", I use their actual initials.