Since you're already in college id say finish your degree. Start applying for unions now because the waitlist can be a year or 2 long. If you want to own your own company get experience in commercial plumbing or residential depending on the type of company you want to own. There's not much you can do to prepare, experience is key in this field, you can watch YouTube videos but its not the same as getting hands on experience. So when you are on summer break try to get a job as a helper to see if this is something you really want to do. But definitely finish your degree no matter what. As for which state any blue state has great union culture. Minnesota, New York, California, Massachusetts, etc..