You should first look for an adult class. At 32 you really don't want to be among a gaggle of pre-pubescent girls!
There are a lot of suggestions that would follow.... If you're in a university town, the college may have extension courses for adults. There you'll find more serious adults interested in starting ballet.
If you're in a larger area that has a dance company, or near a school that supports its own performance group, you may try these.
One thing NOT to do is pick a studio at random from the phone book. "Little Miss Twinkletoes' School of Dance and Basketweaving" is probably NOT the place to pick! If you see a studio that advertizes a director who danced with so-and-so company, or that has indicators like "Ms. Hopkins trained at RAD" or "Member of the Cecchetti Council," there'll probably be a more serious attitude towards dance.
Be prepared to travel to a studio! The closest studio may not be the place.
DanceMagazine, available at most bookstores, like Barnes & Noble, has classified ads in the back for schools by state. These ads are not cheap, so if you find a school there they probably are more serious about training, including adults.
Male or female instructor.... For my two cents, I really like male instructors because of their perspective on the male in ballet. HOWEVER, I would suggest a female instructor to start with. Most male instructors teach at higher levels; you don't typically see a male teaching introductory classes.
Good luck! Please let me know if this helps, or if you need more suggestions. balletboy[/i]