Street Entertainment can take many forms
Walk by acts are typically with the busker providing a musical or entertaining ambiance. There is no distinct beginning or end and the crowds do not particularly stop to watch, for this i would either stilt walk, juggle, or unicycle (or a combination), i am easy going, and find it easy to build friendships quickly with members of the public. flirting with grandmothers, tickling babies acting the fool.
Circle shows are shows that tend to gather a crowd around them. They usually have a distinct beginning and end. Some time the crowds attracted can be huge. You may have seen this style of show in Covent Garden or York.