Whenever I'm workshopping a play I do a few things differently than I would on a regular play.
* Always make absolutely sure that the date appears on all pages. Some playwrights are good about this, and some never remember. If they haven't done it in their computer program, you should write it in the same part of the page (for easy reference) on your master.
* I find that it is best to maintain a master script, in addition to your prompt script, so that if someone for any reason needs a few pages, or the entire script you have a clean copy that is completely up to date to Xerox for them.
* I personally find it is easiest to write my blocking in the left hand margin of the page the text is on when I am doing a new play, so that when you have to replace the page, you don't have to replace the one preceeding it(or following it, depending on which side you take blocking on) as well. You can just line up the blocking from the old page X with the text on new page X if it is even remotely the same text.
* Try to set up a guideline with your playwright of when you need new pages by in order to have the copied for rehearsal. Most will try to accomodate you. Things come up in the middle of the day on occasion (I let my Fringe show playwright do "lunch revisions" sometimes) but you should set up a good working relationship that gets things done most productively.
* When I'm distributing a stack of new pages to my actors, I bind it all together with a Post-it, write on the Post-it the actor's name, the new pages numbers, and any peculiar instructions for inserting them. This helps you keep track of exactly which actors still need to get their packets, and frees you up from having to explain to actors who are called later in the rehearsal day exactly how to insert all the new pages into their script.
New plays can be trying for the actors involved, especially if they haven't worked on a new play before, and especially if the production you are working on is more than a reading and they are required to be off book. I did a play last year as part of a new plays festival and for some reason we were the first show to tech, and the last show to go up, with a week of rehearsal in between. A week in which the playwright drastically overhauled the play. Thank goodness, we'd established that our cast would have their scripts early on, to allow maximum revisions on the playwright's part. It was tough enough to rework the blocking in the week, then quickly put it in to the tech that we'd already done.
You'll learn quickly what type of playwright you're working with. Some sit back and listen carefully, and give revisions and new pages. In other cases you have a second director in the room. Be wary of that. If that's the case pay extra attention to your cast to make sure they aren't stressed out by this double direction.
All this being said, I love doing new plays. I like the challenge of working with a constantly evolving work, and see it progress through the rehearsal process. It can be very rewarding...just don't necessarily expect it to be a GOOD play, especially if this is its first workshop.