Being a singer in a rock and roll band might be one of the ways to fortune and fame, but, believe it or not, not everyone wants the life of a rock star.
There are lots of other ways to be a professional singer, and in this context, being professional means getting paid for it.
Things you must do to be a professional singer
Think of all the women who pack up their bags and their hopes, aiming to be a female singer new york. You're right there are lots of them. What do you have to do to become one of the successful ones? You have to market yourself properly.
Take singing lessons
Your voice is your instrument, so look after it. You need to be able to sing regularly without damaging your voice or your vocal chords. If you're belting it out night after night there will come a payback at some point if you haven't taken the time to look after your instrument.
Consider an agent
An agent may know better than you where the gigs are. Yes the agent has to be paid and that is a downside, but five gigs at 90% of the dollars are better than 1 at 100%
You need a demo tape and video
People need to be able to see and hear you. It is important that potential hirers know what you look like. More importantly, they need to know what you sound like.
Your audio files tell them in a moment what you sing. As an opera singer, you don't get hired to sing a jazz gig. But they also get an immediate sense of how you sing. Make the tape as broad as you can show off everything in your repertoire.