Ok so you have a gig coming up. Its at a wine bar and you know that the area its in is a bit more upscale than the brewery you played at last week. I have a few questions for you. What do you wear? What do you play? How clean is your setup (cords, plugs, equipment, etc.)? These are just a few questions. I could ask more but these are so basic and nobody is getting the hint. So let's focus on these for now.
What do you wear? Easy. Business casual (Polo, Airy dress, Button down shirt, tie or no tie, closed toed shoes, etc.) Why? Because you want to look like you belong in that space and are contributing to the general ambiance. Don't show up in your Metallica T-shirt and denim jeans that look like shit. (I have seen this first hand). Belong there, show the venue and customers that you care enough to look good.
What do you play? Honestly, most wine bars start out kinda mellow. From my experience anyway. It's the second hour in when the ladies and Gentlemen start feeling loose and will dance to literally any up tempo song you give them. Acoustic or full band. You need to feel the room, have options, breathe, be natural, and make good decisions.
How clean is your setup? Generally every event needs to be clean ok people? Tape down your cords, hide unsightly bags, have a designated spot out of site for your beverages, take your empty cups and trash to the right spots so they aren't cluttering your area. Use common sense.
I am so happy I got to experience so many no no situations in previous groups I have played in and with people I have seen when I am out listening to music. You're not winning because you don't look like you are! Don't fake it til you make it. Just do the right thing and you will make it.