What are the businesses you target market?

Networking is probably the best means of generating referrals. Joining a small business networking group in your local area is a great way to gain exposure. The more you are willing to generate leads for someone the more they are willing to do the same for you.   And everyone has carpets that need cleaning...

CDRX wrote: I wouldn't go after any of these businesses starting out as an owner operator. . .  Start with middle to upper end residential and charge a healthy rate so you can make a living at this.  The quickest and easiest way to get off the ground is putting out nice flyers. . .

^This.

Exactly how I started out.  My father started me in the carpet cleaning industry and he's been in it for 30+ years.  He still uses flyers as a marketing mainstay for his business.  You have to get over the fact that you will have to put out a little cash initially for printing and delivering.  Do your research and find a company, possibly locally, that can print and design (if you can't design it yourself) a flyer for you.  Do the same for delivery.  Check into the delivery prices at your local newspaper or free press.  (tbh, I don't recommend wasting time delivering them yourself.  If you can afford a carpet cleaning truck, you can afford flyer delivery.)  It'll take a little elbow grease on your part to get a system worked out, but if you're an owner/operator that's to be expected anyway.
That's the fastest way for you to generate calls and income.  Depending on how many flyers you choose to send out at a time, your first couple of jobs should pay for that delivery.