when I came in as a newbie, the dojocho invited me to participate, told me the training hours, what to pay and where to buy a gi. That was all, and at the time sufficient.
Things about plateaus, the sense of working slowly or injuries came later. I wouldn't have understood them at the time I started, I'd probably have thought that they are stuff not at all related to me. It took me at least four years to understand the value of doing a technique slowly, and two or three to reach my first plateau, which was a very frustrating experience - and at that time, I was enormously relieved to hear from everyone that they had already the one or other plateau experience, too.
All the best,
^this... that's about all a new student can take in in the beginning... they'll be overwhelmed with how to put the gi on, which lapel goes over which, how to tie a belt, etc.
ill usually ask where they found out about the dojo, about aikido, if they've done other martial arts before. then, like steven, i'll launch into my Princess bride quotes, and by then, the first hour is over