3 Requirements to Succeed:

Success may be defined in many ways.

However; most people will agree that success, at least professional success, involves:
-money,
-recognition, and
-happiness/contentment/fulfillment/ sense of accomplishment (in some order).

To be successful as a cosmetologist, here is the path you "must" follow.

1 - School;
Apply yourself for the hours you are there.
Styles change, so what seems important today, may not be a money maker in 2 or 5 years.
Learn everything you can (roller sets, blow-drys, haircuts, coloring, braiding, ethnic hair, business management, customer service, etc., - everything, even if you don't like it).
Someday, when you own your own salon, you will be glad you know it all.

For some excellent information on school life, what to expect, and what to look for:
see the Bellus Academy postings on Twitter.com (cosmetology / beauty), or
www.sandiegobeautyacademy.com

2 - Pass your State Board Exam (the first time);
Get this out of the way so that you can begin your career.
If you fail you can always take it again, but why?
Pass it the first time and move on

For help in passing it "The 1st Time",
www.cosmetologystateboardexam.com

3 - Salon Life;
It is treacherous,
You have a lot to learn,
You need advice from those who know what they are talking about and really want you to succeed.

For a lot of great information on what to do, and not do:
www.modernsalon.com
www.SalonSpa.com
www.salonfixer.com

To recap:
1 - School / learn everything.
2 - State Board / learn the "Secrets" to pass it the 1st time.
3 - Salon Life / learn or die (translation: fired, quit, or make no $).