What a lot of people misunderstand is the difference in Advertising vs Marketing. Advertising sounds like what you're doing - you've mailed out postcards, etc., and are driving around with a car magnet. Marketing educates your customers and future customers on "why" they should do business with you. Have you been able to get "any" customers as of yet? If so, you need to make sure you are getting their feedback and reviews of your cleaning service and post that all over your website. Also, are you on Social Media? Social media is HUGE right now and it's not going out of style anytime soon. Do you have a business page on facebook? If not, you should. And you can use that page to attract a lot of people locally. Also are you listed "locally" on all the search engines like Google Local amongst others.
Are you remembering to "ask for referrals" from your existing customers. Do you have a customer database so you can continue to market your services to them?
Also, here's a resource for you. You may want to check out a website by a guy named Mike Kawula called selfemployedking.com. I don't personally know him but I have networked with him. He is followed by thousands on twitter and facebook. He grew his cleaning business into the millions and now teaches others how to skyrocket their business.
Those coupon mauling envelops may be effective if you find a territory well matched to your location.
The USPS has an EVERY Door program where you can mail over-size pieces to every address on a mail route of perhaps 500-1000 addressees for about 17.5 cents each.
Try Google searching: cleaning service, your city
the results with stick pins perhaps labeled A-G are free Google Places pages, these an be some of the easiest way to be found by people who have never used a Yellow Page book.
You must have a verifiable business address to qualify for a places page, the search ranking of your own business web site seems to effect the results position of the places page.
http://google.com/placesforbusiness/
Take advantage of free online directories like BookMyCity, CitySearch, etc. Make sure you have accurate listings everywhere so clients can get in touch.
It's strictly legal (licensed, insured, bonded), and I've mailed 200 postcards, put flyers on windshields, and a magnet on my car door that shows my company name, logo,
Update : Thanks to all of you guys who took the time to answer my question. Great
