Publicity doesn't have a set budget, but you shouldn't spend more than $50 a semester without getting approval from the EC.
Recommended Methods
GSC anno - announcement list sent to grad students every Monday. Submit by Sunday at noon; event announcements can run for two weeks.
Posters on campus - You should make sure that posters get put up around campus. For more on postering as well as poster designs from past years, see Posters. If you can find students interested in postering inside their dorms, that's also a good idea.
Posters for people to take and share - Starting a few weeks before the class starts, bring posters to Tuesdays. Encourage members to take posters to put up on the door of their dorm or office and to pass on to friends. Also email a link to the posters so people can print their own.
Infinite Display - We can also get free postering on Infinite Display, the large flat screen displays in the Student Center and Stata Center, and for nominal cost, posts on the displays in the infinite corridor as well. We should at least do as much as we can get for free (3 days per semester in the Student and Stata Centers), and possibly more.
Tech Ad - Every student group gets some amount of free ad space in The Tech. http://tech.mit.edu/ads/policies.html Use it!
Dorm Spam - Dorms and living groups at MIT have unofficial mailing lists where people send out email (dorm spam) announcing events and publicizing their student groups. See Dormspam for details. Students are used to getting a lot of dorm spam and ignoring most (or all) of it. Consider asking students to send dorm spam to their own dorms; people are more likely to look at the email longer if they recognize the name of the sender.
Other dance groups - We've sometimes gotten other MIT dance groups (e.g. Lindy Hop, Waltz at MIT) to share information about our upcoming squares and rounds classes with their membership via email.
Facebook Ads - We tried this in 2013. It's unclear how effective they are, but they are cheap and can be used to target MIT students. Create an event for the intro night/ start of class, then ask Tech Squares members to say they are going to the event, then buy facebook ads to advertise the event. This will cause the advertising to be shown more to fb friends of Tech Squares members, in addition to MIT students more generally.
Poking people to email dorms/friends - Word of mouth and personal email are great ways to recruit people. Encourage club members (especially MIT students) to reach out to their friends and bring them to the class. It's easy for people to email friends if you give them a template email they can personalize. Write something and send it to tech-squares-social.
Emailing tech-squares-interest - Tech-squares-interest is a low volume announcement mailing list. A couple weeks before the start of class, check to make sure everyone who has asked to be added to the list has been (i.e. that there are now lists of emails floating around that haven't been added). Then a week or two before intro night/start of class, email the list about the event. Send a reminder email the day of or day before.
Social Media - Tech Squares has group pages on facebook and google+. Create an event, post a picture to the group, encourage people to share it around and invite their friends.
Other options
Google ads - They're too expensive and don't get good targeting. We tried this in Fall 2013.
LSC slides - These used to be more cost effective when LSC did more showings per weekend.