There are lots of acting schools throughout the globe. And, there are many incredible teachers working at these schools. But, just because an acting school might have a great reputation, help teach people who later have success in their career, it does not mean it is the right place for you to study.
Before you even think of signing up for a school, first, you must figure out what type of acting you want to pursue. If you only want to work on stage, then taking classes at a commercial or film based institution would not be good for you.
After learning what you want and what the school offers, then the next step is to investigate to make sure you are getting your monies worth.
I suggest you spend a lot of time at the schools web site. Read about the type of classes they offer, and also spend time reading about the instructors. You want to make sure the teachers have had great experiences in the industry. That does not mean that they have to be famous, but at least have spent some time working in the business.
Sometimes, it is the teacher who has struggled, worked very hard, and decided that teaching is what they really wanted to do, who can help you the most. Famous actors might not easily remember what it takes to pound the pavement, how to market oneself, and what needs to take place at auditions. Those are areas of the industry a very successful actor might not have had to deal with for many years.
If you can, I would ask if you could audit a class or two. Make sure the instructors are teaching their classes in a style that you can learn in.
So, before signing up for classes, do your research, and make your decision based on the content and style of the program and not just a name.