Everyone has different rituals they do before they get up to speak or perform.
For example when I'm acting, I do a physical and vocal warm up on stage before the show. I also do this thing where, after I'm in make-up, hair and costume, I look in the mirror and see the character in me, maybe say a line or two.
When I'm giving a workshop, I warm up as well, both physically and vocally. I also go over my questions: What do I want for the audience? How do I want them to feel when I walk in and start speaking?
What are your rituals? Some people get nervous and find that doing something physical, like jumping jacks helps the nerves because the brain is focussing on the body and nothing else. Some picture the audience naked. Some people have a sound track they listen to that pumps them up. Some do affirmations, etc.. There are no right or wrong rituals. The question is: Are they working?
The important thing about your ritual is that it allows you brain and body to feel ready and focused as opposed to nervous and scattered. Whatever your ritual is, make sure it's doing its job. If you feel ready physically, mentally and emotionally then stick with it! If not, keep trying new things and remember that it's not about you, it's always about your audience. Keep your focus on them!
I'd love to hear some of the rituals you do that work! Please share, you might be helping someone else find a new ritual :-). Also, if you want some ideas, just ask!