A lot of comedians have a special ritual that they do before the gig.
I could construct some sort of a hybrid ritual from comedians I know if you like. You could do 20 minutes of specialised vocal and physical warm-up (not necessarily a ritual, as it can help with performing, though it can form part of a ritual if the reason for doing it turns out to be more psychological than muscle based). Maybe sip a can of Red Bull, wash your hands thoroughly, applying lip salve while looking at yourself in the mirror and doing smiley faces, and being sure to have a certain something in your pocket as a backup plan, or for luck.
I’m not sure I really have a ritual myself. I just rock up and do my thing.
I do a mini vocal warm-up, where I try out the low and high registers of my voice, just to make sure they’re working and have broken in a bit. I also double check I have a plectrum in my pocket, but that’s mainly to avoid fishing one out of my wallet while on stage.
To be honest, the sound-check is a sort of ritual too, often a bit of the gig I most look forward to.
There may be some anti-rituals, though. There are definitely things you should not do. You shouldn’t touch an act who didn’t go down well, in case you get “shit gig lurghi”.
Also, you shouldn’t allow yourself to hate the audience in any way – this won’t end well.
If at all possible, you shouldn’t be seen too much by the audience before going on. That helps preserve the perform/audience distance. There’s nothing worse than seeing someone’s face saying “Oh, so that was the tosspot lurking around the toilets earlier”.
What sort of rituals do you have?