When choosing a karate school, you should consider the following things:

Location
Is the school close to home? Is it on the way between work/school and home? Is there sufficient parking?

Schedule
Do classes fit into my child (ren)s/my schedule? Are there a variety of classes to choose from for different ages?

Atmosphere
Is the school kid/family friendly? Is the school geared toward self defense, fitness or competition? Is the staff willing to work with your special needs?