An opening is customarily cocktails celebrating the mounting of an art exhibit to run over a period of time, usually a couple of weeks. Whereas museum exhibit openings are at least semi-formal, gallery openings are almost always casual. Even if the art on the walls might be going for six figures apiece and there are billionaire heirs or heiresses in the room, the mood is patently anti-establishment at these festivities. Most of the artists in attendance will be in T-shirts. This does not mean they will ostracize anyone in leather shoes (especially if they collect), but it does mean you oughtn’t to overdress.
The first thing you should do is look at the art. You may get a drink while you do so, but don’t hobnob without looking at the whole point of the occasion. If art is unfamiliar to you, just ask yourself how the images, colors, shapes make you feel. Reading the titles may help.
The art world is a bit hermetic—and if you don’t know the crowd, you may feel awkward upon arrival—but it is not a snobbish one. Congratulate the exhibiting artist and introduce yourself. Never ask for any kind of explanations of meaning—except perhaps for the origin of the title if it’s cryptic. Never ask an artist who his favorite artists are. You may ask the artist how long it took him or her to come up with the collection. You may ask him or her to introduce you to the gallery owner or curator. Congratulate the latter as well. And if it so happens the art makes you want to yawn, get over yourself and get a drink.