If I were to work in Mexico, I would choose the upper end of the market in schools. Be aware that Mexico does have low income rates and economic and social concerns. Try and go for the large international schools or chain schools.
Definitely wouldn't get too excited working for a small language school. You need to ensure your welfare is looked after, and can't see the smaller schools being able to do this.
40% of the population are below the poverty line, so don't expect your students to be well off.
I would keep away from the impoverished southern states.
Try these schools in Mexico In Guadalajara- American School Foundation
- Colegio John F. Kennedy
- Anderson School
- Francis Bacon School
- Lincoln School
In Monterrey- Colegio Americano Anahuac
- Colegio Norteamericano Monterrey
- Instituto John F. Kennedy
- Pan American School
- Colegio Latinoamericano
For kindergarten, junior and senior highschools, try the Montessori schools. These schools are throughout Mexico.