Chamber Music

STEP 1: Organize a group of friends who want to be in an ensemble together. Before going to step 2, make sure you can agree on when, where and how much you want to rehearse together. If you cannot agree on these important elements, you will probably need to regroup with people who have more similar interests.
STEP 2: Find Music Options. To see what is available, Google the genre of music, such as Cello Sonata, Viola Duet, String Quartet. For more unusual instrument combinations, google the words "Category: For" followed by the instrumentation of your ensemble. For example, "Category: For 3 violins" OR "Category: For 2 violins, 2 violas, cello" or "Category: For 2 violins, double bass." Wikipedia also has lists of repertoire that may give you leads that you can use to search in other locations.
STEP 3: Select a piece that interests everyone in the group, and that is playable by everyone in the group.