How to become a model?

I have looked online and there are SO MANY "modeling agencies" and "casting calls" out there that I don't know where to start, and where to look. Some people say certain companies are scams, some don't. Some say it's useless to give them your information online (if you want them to even consider you for modeling), some don't. I just don't know where to start. Like, what's the first step I should take? Please help.