A real business?

I have finished one online class and am now on my second one. Got an A in the first class, but this second one, the professor seems to be a stickler. But we'll see...

So, I really need to get my business going and start marketing and promoting it. I have to write a real business plan and get things in gear. I'd love it if I could have a steady source of income, even if it wouldn't be enough to pay the bills, but at least pay for my etsy addiction lol. Anyone have advice on this or some tips? I have the summer to do this, so it'd really be the perfect time to get the ball rolling for real!