If one goes to a play, all they will see are actors portraying characters. They will see a nice stage presentation. They won't see the preparation. I wasn't very good in building sets. There are people that do it for a living and are great at it. I admire them. Just like when I took shop in junior high, I was always off 1/16th of an inch. Actors generally don't have to build sets. That is a blessing.
Actors need to exercise before coming out on stage. I learned many techniques to relax my muscles, as well as to get my adrenaline up before a performance. Despite my great stage fright, I found that exercise helps ease the doubt of doing good on stage.
Two of the techniques I have used involved rolling my shoulders and shaking my hands. One was for releasing tension, while the other was for releasing nervousness. Another technique I learned through meditation. Tense muscles and then relax them. Start at your feet and work your way up to your neck. It takes a while to go through that process, but it is good to prepare your body for what comes next. Sometimes, I would jump up and down to get my blood flowing and build up my energy. It may look strange to some, but it helped me get ready, especially if I had to do something physical on stage. In one play, I was playing a thief being chased by a policeman. The chase was offstage, so we both ran around backstage until we were out of breath. Then, we came onstage to make the chase look believable.
When I was a senior at Presbyterian College, the wife of my drama teacher was into yoga. She taught us relaxation techniques to loosen our muscles and joints. I hadn't done yoga before, but I found it very helpful in preparing for the physicality of acting. Much of it was an add-on to my meditation work.
The last thing I would do, before going on stage, would be to find a dark room backstage away from everyone else. I would sit in there for a few minutes and think about what I needed to do. Then, I would say a prayer. God gave me my talent for acting. I would thank Him and ask for courage and clarity of thought. I would then pray that the audience would receive what I was about to give them. That prayer would calm me down, and then I would be ready to face the audience.
A lot goes on backstage. It can be very chaotic. There are people to make sure you enter the stage at the appropriate time. There are make-up people to make sure you look good. There are costumers to make sure you are dressed properly for your character. Wardrobe changes may have to be made quickly. There are prop people to make sure things are placed onstage for the actors to use. All the while, there is the actor getting ready to present a good performance with the help of others who don't often get the praise they deserve.