As we've talked about many times, superstitions often arise out of the fear of uncertainty or the fear of failure. It would only make sense that musicians would have superstition regarding their live performances. On the website Independent Music Promotions, they explored some superstitions specific to some well known artists. Some of these are confirmed while others are mainly just rumored.
One Direction is said to share a bath together before a performance. Personally, this seems a little far fetched and was probably concocted from the mind of one of their more… let's say enthusiastic fans. Keith Richards of The Rolling Stones has to eat a Shepard's Pie before a gig. Adele apparently suffers from stage fright and has created an alter ego for herself when she performs, who she calls Sasha Carter. This actually doesn't seem all that unusual to me given that we have David Bowie and Marilyn Manson. It's said that Ke$ha has her crew strip down and roll around in oil and glitter before shows. Not entirely sure whether I should believe this one or not… And then we have Led Zepplin. Robert Plant apparently needed a space in which he could iron his shirts before shows.
Teen.com also did an article exploring different artists' pre-show rituals. Lorde apparently has a lucky blanket that she naps with before shows. Beyonce is known to sit in a massage chair while her hair and makeup is done (which seems more like a comfort thing than a superstitious thing) and she sometimes prays before she performs. Paramore is also a fan of prayer before shows.
To me it makes a lot of sense that musicians, or really any performers, would be superstitious. It's a high stress situation and they have a lot of pressure to perform well. While many of these little rituals realistically have very little impact on their performance, if it eases their minds before a show I don't see the harm. It's very much a placebo effect. Performing their rituals makes them feel more confident, and then, in turn, they are able to put on a better show because of it.