The unknown is scarier than the dancing, so here is the whole hour, laid out in advance. This is specifically how the free introductory session runs at our studio; other schools differ, but the shape of a good first lesson is fairly universal.
First: a conversation, sitting down
Your teacher asks what brought you in, a wedding, a promise to yourself, a partner with momentum, and what you are hoping for. They will ask about music you love and any worries you are carrying, the no-rhythm belief chief among them. Nothing is judged and nothing is a wrong answer; this part exists so the dancing that follows is aimed at you.
Then: a little dancing, gently
A basic step, on your own first, at talking pace. Then the same step with your teacher as your partner, then with music. That is the whole ask. You will not be flung into choreography, there is no group watching, and mistakes are treated as information rather than events. Most people are quietly startled to find they are dancing, actually dancing, inside twenty minutes.
Finally: an honest recommendation
Your teacher sketches what a personalised program would look like for your goals, your starting point and your pace, and answers the practical questions, including cost. Then you go home and decide in your own time. The session is free and the recommendation carries no obligation; the studio's whole model depends on the first hour being good enough to speak for itself.
How to prepare, which is barely at all
Comfortable clothes and walkable shoes, covered fully in what to wear. Bring a partner or do not; no partner is needed. Bring the song, if there is a wedding involved. Mostly, bring the version of you that finally booked it.