Sometimes you will have opportunities to watch a performance a couple of times and get a feel for the performers movements and when they interact with the crowd.
I love to use my Nikon 105 macro lens, not only for portraits but also for close ups. The image of the musician playing his guitar was taken with my 105 Nikkor lens. This gives you the ability to be further away from your subject but also once you have built up a rapport with the performer, you can move in close.
Also, at street fairs you will find images that just happen. You will be looking for a preconceived image in your mind and you will look up and see serendipity playing a big roll in helping you make good photos.
Don't forget the close up details that also tell a story at fairs and parades.