What can you expect when you come to a filksing? There's a lot of variation, but most of them are generally like this. People get together, bringing instruments and printed or electronic songbooks if they so choose. People take turns singing. They may sing songs of their own choice, or someone else may ask them to sing a particiular song or something related to a topic. Accepting requests is polite, but there's no obligation.
A "housefilk" is a filksing that's held in someone's home. Most of MASSFILC's gatherings are housefilks.
People often sing along or help out with accompaniment. If you'd rather they didn't, you can ask them not to. Sometimes people do group performances.
There are several ways the circle can proceed. The most common at MASSFILC meetings is "chaos," which means anyone can sing after the previous person has finished. If more than one person tries to jump in at the same time, they work it out among themselves, or a member of the group may act as moderator.
Being a "filkhog" by singing too often is considered impolite. The more you've been singing lately, the longer you should wait for someone else to take a turn. Some people are shy and need encouragement.
Sometimes there will be a "bardic circle." This means that the turn goes around the circle, and each person may choose to "pick (make a request), pass, or play (perform something)" in turn. This style encourages timid performers, but it can take a long time to go around the circle in a large group.
A variant on the bardic circle is the "poker chip bardic." In this version, people get poker chips or other tokens. After each song, anyone may throw in a chip to pick or play. After using a chip, they have to wait till the next round to perform again (unless someone else uses a chip to make a request).
You can perform any kind of song at a filksing. There's no requirement that it "be filk," whatever that means. Unless you get unusually offensive with your choice, no one will object. At most, people will quietly move to the snack area or take a walk outside if they don't like your song.