Choose a space. You’ll probably want to run your underground biz from your apartment or studio, so your living expenses—like phone bills, utilities and rent—double as business costs. If an existing gallery piques your interest (say, a West Loop gallery that shows like-minded unicorn paintings), move nearby. You’ll want to attract a critical mass of gallerygoers.
Make it appear legit. Even if you’re on the down-low from the good ol’ government, you should dignify your artists with loan agreements. Post some sort of signage (unmarked buzzers in dark alleys are easy to pass over, not to mention sketchy), and always hang a list of artists and artwork titles in the gallery for viewers.
Get the word out—but not too much. Send e-mails to friends and press releases to cultural publications. Don’t post a sandwich board; it might invite unexpected visitors (e.g., winos, cops).
Clean up before exhibition openings. ’Nuff said.
Openings should have a finite time, say 6–8pm. Don’t let it turn into a party—partygoers could trash your place, which puts artwork in jeopardy. On the other hand, if your purpose is a party, make sure ample gallery attendants and volunteers look after the guests. Stay sober; you need to represent your product…and not get robbed.
Make the booze free. It’s tacky to charge for thimble-size cups of cheap beer and watery wine.
Keep regular hours. If you can only sit the gallery on Saturdays or Sundays, that works. (But don’t solely open odd hours on weekdays—that makes visits unfeasible.) Remember, you made a commitment: No closing the space during open hours no matter how hungover you feel.