There is a difference between watching and doing magic tricks. When you are part of the audience, you are there to enjoy the show but when you are on stage, you have to give an amazing performance or else be booed by the crowd so when it is your turn to do the tricks, you better be ready.
Preparation is key to be able to perform a good show. You have probably mastered a few tricks already so all you have to do is figure out which ones will be part of the act. If this is your first time, make sure you can keep the audience entertained for 9 to 10 minutes.
You can time this and practice your act in front of a few friends. If they like it, then there is nothing to worry about but if they have some comments and suggestions, listen since this could help make your performance more interesting.
First time magicians dont always have to choose the venue for the magic show because there is one already so you just have to sign up. This is sometimes known as amateur night where magicians, singers, dancers and other artists are able to make their debut. Be sure to come early so you can relax before it is your turn to go on stage.
If you want to pick your own...