While a room owner is responsible for keeping their room profitable, a wise musician understands the necessity to help feed the room. Essentially, no rooms, no gigs. Even where there are private parties, unless one is aware of the realities of being the fire in the corner, they will hurt the business and themselves.
1, Ready. Equipment works, band is sober, songs are learned, yadda. Scope out a room before you play it. Look at the electrics, the lighting, the number of seats, the regulars. If you can do this a week before you play there or at least with enough time to make any changes you might have to make like leaving the extra lights and big amps in the van because as soon as you crank up, the switch box fuse blows, you can avoid a small problem or the kind that costs the entire gig. And that hurts a lot. People remember bad much longer than good, This is just good sense.
2, Appropriate. All acts don't work in all rooms. If you are a big hair really really loud piercing band, Bob's Country Bunker is not your gig. If you are a really quiet, thoughtful singer-songwriter, the corner bar may not be your gig (too sleepy). You may be a coffee house act. Is your material appropriate even then if the room is "family friendly"? If half your set consists of bawdy risque songs, or "I want to kill my girlfriend and then off myself or maybe not myself" (real depressing even for coffee drinkers) songs, you may not be. See item 1: go see what is working there and think before you book. Or work with multiple bands. Many full time players do this and just make sure these acts don't compete with each other. Bad blood is bad blood, And if everyone is working for tips, work for tips. If you go in demanding more money than the room can support because you are That Good, you suck. Even if they are foolish enough to promise you that, if they lose money you will lose the room. No rooms; no gigs. This will hurt you and hurt others. Set your price and if they can't meet that, move on. No harm; no fault, but don't book the gig with expectations that the room can't meet. And more important, don't set expectations you can't meet.
3. Consistent. You really hurt the room if you don't have your shit together that night. This is more than ready: it is a sense of how your songs work together, or simply, what your act is about. You are not a laptop with a playlist. Think through your sets but be ready to adjust according to the mood in the room. Don't make it hard for the rest of the band to keep up having to make too many adjustments too fast and if necessary, be sure someone (if not you, someone who is good at this) is at the mic filling dead air. Know when to turn down or turn up. Don't play crazy at the end of the night in a room where people drink heavily. Fights are bad for you and bad for the room. Don't feed hecklers and trolls and don't let them get to you. Stay out of the conversations going on in front of you. A discreet distance is a good thing, not stuck-up, but professional. The wait staff can work with you or against you and YOU DON'T WANT THEM AGAINST YOU. The wait staff is the front line of your continuing success and publicity.
DON'T QUARREL ON STAGE. Ever, An audience can smell it a block away. If personal problems are getting out front, it is time to stop gigging with this band. If you are fighting with yourself, keep it entertaining.
4. Crowd smart. Some crowds simply cannot be mixed. Like appropriate, if your following is middle aged wine drinking talkers, don't take them into the room where the beer drinking rowdy souls hang out. Don't mix the hippies with the truck drivers. Kumbayah sounds good but it doesn't work. Don't go to the mic and talk politics or religion unless you are in a room where a lot of that was going on when you got there; or that is what your act is about. Even then, watch it. See item 2. You may have friends you care a lot about but who insist on bringing their personal dramas or professional agendas to your gigs. This is a very tough one to handle but you will have to or the room owner will and that may not work out well for your friend.
5. Butts in seats. You really really really are responsible for finding and caring for your fans. A good sound, heck an a-list sound without a following isn't going to last long. The room owner may love you but he or she or they are there to make money, not promote bands. Again, the wait staff can help you or hurt you so try to help them make tips, and don't start trouble they can't handle.
6. Don't talk down your competition particularly if they are working and you aren't. It's not just bad form, the more rooms that have acts the more rooms that need acts. Some people both young and old believe it is a zero-sum game and if others are working they won't be. It is exactly the opposite, so don't resist recommending your competition as long as you know they meet the other requirements to play the room. Also, when you are older, those people will be your tribe and most of them will be your friends. Over a long career, you are more drawn to the people who do what you do, not the audience that likes you. "Life is a long song", to quote Tull.
7. Pick your art carefully. Being open to all life experiences turns out to be unhealthy and you need to be healthy to do this. It is physically and mentally demanding. Pick material you want to perform. A top forty house band is a terrible way to live and wears through your soul because it is so repetitive and you become a monkey with an electric box on your tail. At some point you will do this kind of gig and my best advice is to figure out how to get out of it. It's a trap and you will fall into the mode of it being a job. It is right to be a professional but in which profession? Nothing feels more like prostitution than singing songs you hate. Really. And you owe the songwriter not to do that, Really.
8. Be on good terms with other artists doing other media. The digital illustrators are your best friends and you can recommend them to other bands and other room owners who need ad work, posters, band photos and so on. Wherever there is a healthy performance scene, there is a healthy ecosystem of expression, common themes, common reputations and common conversations. Seek out, recruit and work with other artists. Collaborate.
Actors? Maybe not. Whiny. :)
9. Be aware. Many rooms, owners, bands and people have side gigs. It is all too common for those to be the vices: drugs, sex and gambling. Unless you involve yourself, they will usually not involve you but once into the games, it's hard to keep your business and their business separate. Stay smart and don't discuss what you don't want to be involved in. There are many forces at work here from the owner to the local vice squad to the crazy person one shot away from going postal. Be careful with charity events. Ask questions. Too often people organize these for special events in rooms and the money is not going where promised. It's good to be a community contributor but don't be a shill for a con. It is unfortunately common and an easy gummy bear to get stuck with.
10. Do not bite the hand that feeds you. If you are working a room on a street regularly, are respected and it's working, don't go to the competitor across the street to book a free weekend. You are drawing from one room into another and the owner will notice. As long as you are respected, return respect.
It's all simply good business. Stay competitive, refresh your sets with new material, don't let slack invade the practice and so on but keep in mind that from the room owner's perspective, the money in the cash register is the ultimate decision maker and you are part of that formula. Don't let them make you feel responsible for all of that because many a room owner is also an idiot in the wrong business and you want to stay clear of them, but what you can do that is good for you and good for them, do. Again, no rooms; no gigs.