First of all, you have to have a venue, a spot, somewhere to read, some safe space (safe being ‘welcoming’) to hold a reading. To read. To stand before an audience and ‘express yourself’ of to allow the poets to display their art to the world. It need not be a large venue, though it should accommodate your audience. Comfortable chairs would help, though I have been to and read in venues where the audience improvising and just takes in the literature on the floor. However, chairs, I am sure, are welcome, especially if your audience includes older attendees.
Of course, you might need a microphone, or a podium, or more accurately, a space from which the poet (or poets) shall read, or shall draw attention from the audience. The poet does not have to follow the script of standing before the audience for the entire performance (reading) but there should be a spot where the audience expects the reading to begin, where the poet shall start the literary journey.
Of course, you also want an audience. That is the reason for it all. Some exchange. Some socializing. Networking. Exchange of ideas. If people are reading, (open mic), have a sign up sheet ready, and something for everyone to sign so you can do more events in the future. You want to tell people about the events, in other words, the next great reading you will organize.
Finally, as many have said, you should have something that will happen, after the reading. The author will sell books, do a Q & A, people will socialize. Might want to roll out some snacks. Wine and cheese. Cookies and cider. Personally, I say, shoot high and put some booze out and some decent food. Nothing weak. Give them a spread in other words. Booze for the drunks. Cider for the suckers. Swedish meatballs? Wings and mumbo? Ok, I am getting out of control. But this is your reading. How did it go?