Once you get past finding possible schools that will meet all of, or most of, your families needs, you will be ready for the tour.
When vetting possible schools, here are some important things to look for:
1. A reasonably clean environment. Obviously in a school filled with small children you are not going to find a place you can run a white glove over. Nevertheless, the cleaner the better. You want to see kids washing their hands or at least know it's a part of the schedule. Nothing prevents illness like hand washing.
2. Do the children look happy? Are they interacting with each other? How about with the staff? Keep your ears open.
3. Ask about discipline policies. You want to know how problem situations will be handled. What will they do if your child is bitten? If your child bites someone else?
You want the schools policies to align with your own as much as possible. If you are a strong disciplinary and this school doesn't even have time out, this will inevitably be a problem for you. If on the other hand, you don't believe in ever saying no to your child and ALWAYS give them choices a school that is very structured or that gives a time out with one, or no warnings is going to be very difficult for your child and by extension you when your child cries and fights you all the way to the classroom door, the director is calling you and the teacher always has something negative to say when you pick your child up.
4. What's the staff turn over rate. Now just so you know ECE is not a well paid filed and is often a high stress job. The average pre-k teacher stays in the field 3 years, at least that was the statistic a few years ago. So as long as the whole staff isn't new and at least half of the staff has been there 2 or 3 years, it's probably OK that the other half just started.
If the staff is all new, there may be a problem with the management/owner/ corporate. Good schools retain there staff.
5. Come with a list of questions prepared. Ask about anything that matters to you, or that pops in your head as the director walks you through the school.
Also important is to get the licensing number of school. In California this number allows you to get information from county licensing department. This will let's you find out if any complaints have been filed against any staff member, or if any infractions have been made. Some are small like parents didn't sign children into school. Some are not, like toilets weren't working properly.
If the they are reluctant to give you number, I would consider this a red flag. Check to see what regulations there are in your state. California is often thought of as a tree hugging hippie state, but we have some tough laws and a lot of regulations. I don't know that all states have regulatory bodies that check the schools out on any sort of regular basis, I'm assuming here folks. Don't let me make an ass out of you. I'm thinking of Florida mostly, they're crazy there.
At the end of the tour you should receive a parent handbook as well as paperwork for enrolling your child and a deadline (usually a week) to decide if this is the school for your child. READ the handbook, if you have any questions after that call and ask. If this school does meet all or most of your needs, checked out with licensing then you are ready to enroll.
I hope you found this helpful. If you feel like I left something out or you have any more questions. Please leave a comment and I will answer. Good Luck!