Hmm.
Well, there are plenty of online resources out there, including videos and articles that may help you to improve. But can I make an earnest request? Please, please, PLEASE go to lots of different sources, try out conflicting theories and see what works for you personally - if it hurts, if it disagrees with your fundamental idea of what is healthy for you, don't do it. I take vocal lessons and coachings through my university and some of the "advice" that I see on the internet, in comparison to what I learn from qualified teachers, seems downright dangerous.
To be honest, I think that if you want to work as a musician you need to also recognise that it actually is like any other job - if you're really interested in making good money out of it, you'll make the initial investments of time and practice, but also perhaps money. So don't necessarily reject the idea of vocal tuition straight away; it can save you a lot of time and even your vocal health.