Ask them what activities they do and the ages/number of other children they have at the same time as yours. Also, some will pick up from local schools and preschools, some won't. May also be worth asking about their holidays, as you'll have to make alternative arrangements then. I think your child is still a baby(?), but I would also ask how they discipline children that are misbehaving.
In the end, you'll go with whoever you feel most comfortable with, who has a similar outlook to you. Good luck!