Basically, just show up! You don't have to call. If you want to ask any questions, show up a bit early, so as to not delay the Sensei from starting the class
Act as you would if you were observing a class in high school. Don't talk a lot or interrupt the class. Someone will probably come up to you to see if you need any help.
It's okay to walk around or to use the bathroom. Please don't just walk into the dressing rooms.
In our dojo, it's perfectly all right to come in late or leave before class finishes. Other dojos might have a different policy.
Don't be afraid to ask any question. A good teacher will be up front as to what the dojo’s fees are, or who they trained under . If the dojo is part of an Aikido organization, feel free to check on the teacher's credentials.