Neal, try and find a course on "education and the law." That will give you some great prep for your legal responsibilites as an educator.
Second, I learned the hard way, that history teachers are a dime a dozen, so diversify your certification. Certify in math or science and you'll be a shoe in. Maybe even Spanish.
Be ready to be forced to teach things you're not certified in.
You may sign up for History/social studies, but you may wind up teaching other things you won't enjoy.
One of the ways to get your foot in the door is to substitute teach. If a principal likes you, they might hire you on if they like you or need you bad enough.
I saved all of my textbooks on teching/lesson prep, but they are for foreign languages.
Oh, wait, just thought of this. With your background in petrochemical industry, you would make a great chemestry teacher.
Build on your work experience and background.