In the leaflet itself, ask people to pass it on to someone else or post it. Have more than one person leafletting at once. Be ready for rejections, as many people will ignore you, and even make snide remarks. Newspapers You can put ads in your school newspaper, but the price is usually high, and such ads are usually not as effective as posters. There are other ways to use your school newspaper for publicity.
Many school papers sell much cheaper classified ads.
Many also have calendars of what's going on around campus, which list events for free or cheaply. Letters to the editor and even guest editorials are a good way to publicize, if you don't make it a completely apparent self- promotion. One group ran classified ads that pretended to be a dialogue between two lovelorn people flirting with each other. Everyone read and followed the saga. Some school papers are so starved for news that they will even do an article about your upcoming event.