Decide what type of teacher you want to be. There are different qualifications required to teach different grades, but more importantly, you should decide which career path you want to follow. Speak with different teachers of varying grade levels about volunteering to help in their classrooms. This will give you a better idea of your strengths and weaknesses when it comes to teaching.
Contact your state's Department of Education (see link in "Resources") and ask what specifically is required to receive a teaching certificate. States tend to differ quite drastically on what's required for teacher certification. And some even have alternative certification routes that allow you to teach before or while you are getting an education degree.
Complete the required coursework. Even if you have a bachelor's degree, you may still need to complete another year or two of school. Otherwise, there may just be a few specific classes that you need to take, in order to obtain a minor in education.
Study for the Praxis exam. Potential teachers are often required to pass this exam, or an exam similar to it, in order to obtain a teaching certificate. Reading, writing and math are all covered in the exam, so brush up on your skills by studying a Praxis exam book (see link in "Resources").