Being a stage manager usually means that you are the “top dog” of the production — the king, so to speak. But if you don’t treat your “subjects” with the respect that you deserve then they usually have the right to walk out on the production — leaving you to explain your actions to the real head honcho: the director. (Who won’t be too thrilled that so-and-so just walked out.)
Given that you will primarily be working with the actors and the director for most of the production, making them happy is one of the higher priorities. The director has the simplest pleasures on paper: keep everyone on track during rehearsals, keep the production bible (your copy of the script) up to date, and no backseat directing. It’s one of the easier ways to keep the director happy — and keeping the director happy will make everybody happy.
The actors are another (sometimes more expensive) story. As I have mentioned in this post about making your first kit, most of the kit you will have primarily revolves around the communal items that are usually in the green room — i.e. the actors room. Doing this will usually make the actors “like you” in an indifference sense, since they know that you are only doing this to look after their well-being. Some stage managers will leave their involvement with the actors at that, since their idea of being a “good” stage manager requires them to only “look after their physical well-being”.
What I always try to do with my actors is look after their “personal interest” as well. For example, in my last show Molly (real name?) had to wear this comically large bow hairband that she would claim was heavy to wear (the director refused to drop the bow from her costume). Therefor I made her a deal where, as long as she walked out wearing the headband, I would look the other way as to when she would put it on. Working with the actors in situations like this allows them to understand that you care about them, and not just about how they are doing “physically”.
Now we have to talk about the designers. From my personal experience working with them — this goes across the board with costume, prop, and lighting designers — it is usually best to let them do their own thing, in most (if not every) circumstances they know what they are doing better than you are. The only circumstance when I had “direct input” over something that they had to do involved a costume that was still being washed right before a show — allow the piece to stay in the dryer and risk it not being done in time or put the actress in an alternate costume for the scene? It should have been done the night before, I will admit that, but there are times when things get noticed right before the show — this was one of them.