I am interested in becoming a model, and am looking for a good way to start. Any suggestions?

I went to an open audition with my younger sister yesterday. It was a big event, looking for actors, models, singers and dancers. My sister got a callback, but as I had decided to go at the last minute and admittedly looked very unprofessional, I didn't. However, I would really like to start modeling and want to find a way into the business that isn't a complete scam or that will cost me a ton of money that I don't have. I have been trying to research agencies and events online, but it seems that every single one I find that looks nice in the beginning turns out to be a scam, or it is being run by a former child abuser or something. Does anyone have any suggestions or adivce, either with modeling itself or how to find jobs and build my portfolio?