Here'* how it goes in Michigan, I can't speak for your state....I'm almost done, just for reference-I do know this very well.
You must be enrolled in a Bachelors program, Secondary emphasis for what you want. You'll need a teachable Major, and more likely then not a second Major or a minor (ideally teachable too). Teachable Major=one that your college has a teaching program for and your state has test for. It'* been said before that Math and Science are good. They are, those are mine major and minor. If you are willing to be flexible...like move, you'll find a job (FL is really looking, as is Arizona).
Midway through your Bachelors you'll need to apply to the College of Education if your school has one. For me, this was not a big deal. This just ensures you are on the right track and that you have nothing that would obviously bar you from teaching in the future. At this point you may need to take a test. We have the Michigan Basic Skills test, and when they say basic, they mean basic...no biggy there.
Toward the end of our program we then had to take our content area tests (for your major and minor). These were harder, but not impossible by any means. Then you apply to Student Teach, do that and come out with your provisional. In Michigan, this means you have about five or six years to get 18 credits of continuing education. This is when people start earning their masters since they are taking classes anyways.
I have had a lot of rewarding experiences, and I'm still only in my student teaching. If you have any questions, feel free to ask. I don't know everything, but trust me I've learned alot along the way.