For instance, guests often express concern about learning all the songs and choreography. Assure them that they'll be given help and that they'll have time to learn everything at a reasonable pace. If the subject of competition comes up, discuss it as one of the major events for the year. You might mention that although it's not a mandatory activity for every member, most members choose to participate because it's lots of fun. The work put into competition each year helps the chorus continue to improve.
Many people are concerned abaout the time commitment.
If that fear is expressed, acknowledge it. Each individual needs to examine the organization with her schedule in mind. You might explain that many of the activities are optional and that although regular attendance at rehearsals is expected, individuals may participate at whatever level fits their schedules. Do a lot of listening. It's much more important just to stay near the guest, or not to leave her alone, than it is to talk.