Over the years I've learned a few things about playing in pit orchestras for musical theater and I wanted to pass these along...these apply mostly to electric guitar players (obviously) but I suppose they can also be applied to electric bass as well. Remember that playing in a pit band is just that: a "band" - it's not a solo project - so be respectful of those around you who are also there for the job.
Some of the most important things I've learned should sound rather basic but you'd be surprised at how many people don't even learn the basics. Pretty much all of these points can be boiled down to one general rule: have some respect for each other in the pit. Master that, and all of these points should be a natural consequence.
1) Show up on time. Whether it's an orchestra run-through, a sing-through with the cast, or (especially) a performance call - be there on time or preferably early. Depending on where you are sitting physically in the pit, it may be difficult to get in and out if you're late and you have to step over everyone else to get to your spot. But it's really frustrating (and stressful) for the Musical Director if they are unsure if you're going to be there or not. Save yourself and others the grief and just prepare to leave a little sooner when possible, so that you can arrive early, set up, tune, and be ready to play.
2) Line up your subs. Life happens, and you never know what might keep you from being able to show up at a gig (sickness, accidents, prior plans). It's a good idea to have at least one or two names of other players you can trust to show up in case you need to miss a service. And don't think "well, it's just a rehearsal; they won't need a sub for that" - wrong - any one part that's missing will make the rest of the orchestra sound incomplete. In fact, part of the rehearsal process is not only for the cast to get comfortable learning to run the show with the musicians, but it's also for the sound people to get the levels correct, for the MD to hear how everything sounds together, and for the rest of the orchestra to hear how the pit will sound. So if you know in advance you will miss one or more service, be sure to have a sub lined up.
3) If you get the music ahead of time, know your parts! Don't show up to the first rehearsal having never cracked open your book. Unless you're a killer sight-reader and nothing fazes you, or if you've played the show a dozen times before and know the book by heart, put in enough time ahead of your first rehearsal to learn your part. If you have access to a recording of the show, mark up your music to know when to switch patches or effects pedals. I like to use my Boss GT-8 and program the whole show as much as possible based on what I hear on the CD, and then I'll just make patch change notes in the music when I need to switch to a different sound...but I'll do all of that ahead of time whenever possible. It's not just a matter of learning the notes but also knowing when the patch changes are coming.
4) Practice quietly in the pit. I've been in a few pits that sound like you're walking into your local Guitar Center - the guitar player has his amp at full volume and is trying to impress with his Yngwie Malmsteen shred techniques, or the bass player is trying to show off his hot funk grooves so that you can hear every slap and pop (or the drummer is trying to do his best John Bonham impersonation). Trust me: you're impressing nobody. Worse yet, you're coming off as arrogant and rude to the other musicians around you who are just there to play the gig. I understand sometimes you do need to test your levels - fine, turn up and test your levels for a few chords but then turn right back down again. Practice at very low amp levels; others around you should still be able to carry on a conversation while they're waiting for the show to start. I've even seen some guys wear headphones while they are practicing; I'm sure that helps them concentrate better anyway. Just be mindful of the others in the pit when you need to warm up or practice a particularly difficult part of your music.
5) Don't clutter your area. This might be difficult if you have lots of floor pedals that you need to rig up or if you need lots of axes to switch throughout the show. But whenever possible, don't try and claim a huge space for yourself. Chances are the pit you will be playing in will be small and you'll be pretty cramped with other musicians who need their own space as well. Use as little room as possible while still making sure you have all of your gear accounted for. Sometimes you might need to apologize up front to your neighbors: "Sorry, I have a lot of gear here but I'm trying to not get in your way" is usually a good sign of a conscientious player. Also, when you bring in your gear to each performance, get rid of the cases as soon as possible. Others will be trying to set up as well and they don't want to have to climb over or work around your instrument cases to do so. I like to bring my guitars in one by one, put the guitar on a stand and then take the case out to store outside the pit...then repeat for each instrument I am using. Keep your area tidy. For stomp boxes or pedals, try and keep your setup compact as much as you can while still making them usable (nothing is worse than hitting the wrong effect or stepping on multiple boxes at a time because they're too close together). Invest in an all-in-one board (like the units made by Line6 or Boss), if you can afford it.
6) After the gig, don't try and be the first one out of the pit. If you know ahead of time that you need to run as soon as the last note is played, tell those around you that you have a special circumstance and will need to bail quickly - they'll be understanding and will have appreciated the heads-up. What they won't appreciate is you jumping out of your seat and climbing over everyone to be the first person out without any warning.
7) Don't call any other player out regarding their part. This should be obvious, but surprisingly that's not always the case. Unless you are a section leader and you might have some helpful suggestions to the other players in your section, it's best to leave that stuff to the MD. I played in one pit where a brass player kept pointing out the mistakes made by a violinist. He was really being an asshole about this. After a few instances of this, the string player turned around and yelled at the brass player to mind his own parts...and things just got a little tense after that. If you're not the MD, it's not your place to say anything about anyone else's playing. If the MD doesn't like what that player is doing, they will let them know. Just stick to your own part.
8) Be mindful of other people's instruments. You might be playing a cheap acoustic guitar for this show, or you might be using a road warrior bass (you know, the cheap one that you don't mind if it gets dinged-up a little). But keep in mind that some of the other players in your pit might have paid a whole lot more for their instruments. Some of them might cost the same as the car you drove to get to the gig. So be careful of other people's property! If you carelessly walk through the pit and knock over someone's beautiful bassoon or trombone...well, I wouldn't want to be you in that situation.
9) Watch for cues! It's happened to a lot of us - you are vamping the same chords for a few minutes while the action is developing on stage and your mind wanders and you don't watch for the cut-off cue - and you end up playing a solo when everyone else has already stopped. Embarrassing. Awkward. Don't do this; if necessary, put a big symbol on your music to watch for the cues so you'll know to pay attention. And don't automatically assume "each night this vamp usually plays for about 10 measures" - it's live theater. You never know when you might need to cut off from one night to the next. Save yourself the embarrassment - just pay attention to the person with the baton. It's not hard.
10) Watch your volume. This not only applies to while you're playing, but just as importantly this applies to watching it in between songs. When the song ends and the applause dies down, be sure your volume pedal is silent or your volume control is all the way down BEFORE you take the guitar off and put it back on its stand. Nobody in the audience (or in the pit) wants to hear your open strings resonating at full volume because you forgot to turn down. They don't even want to hear your hands brush the strings. Once the music stops, the audience shouldn't even know you're down there, so keep silent and pay attention to your volume or pedal settings in between songs.
Again, most of these things should be self-evident to any mindful musician but these are the things I've seen in pits that can make things difficult for you and others.
If anyone has any other tips they'd like to pass along, I would love to hear them - leave them in the comments so others can see them too.