First - congratulations on your first paying gig.
The second thing I would say is never highlight. Always work in pencil - things change all the time.
I like to write down all blocking, esp. when the director says something very specific (ie. make sure you're at the door by this line, or look at so and so for this line, etc).
I also track props (where they come from, who uses them, where they end up, etc.). I also do the same thing for costumes, esp. if there are costume changes on stage.
And then the big ones, lights and sound cues (and any other types of cues the show may have). Sometimes sound cues are obvious where they will be (ie. the doorbell rings). Before you start tech speak to the sound and lighting designer and see if they have a prel. cue list that you can start to put in your book. And then expect to add more cues during tech.
Good luck on your job