One thing I could say is that if you're hoping to make comic as your main income in life, is that you're taking the hardcore way to get an income.
It's very hard to get on the level where millions of peoples will read, care, invested and eventually pay for your story if you yourself didn't seems to care about the comic itself but caring more with the $.
I could advised you to try doing commission, it will see you extra money than in making comic if your intention is purely that.
And I'm sorry if this sounds harsh, but this is just the truth for me.