The best practical way is to go from office to office handing out your
business card or brochures. Instead of trying to "make the sale" try to sell
an appointment to come back when you can sit down and talk with them.

In my point of view, Local optimization can help you to grow your business.

Most businesses choose a location that provides exposure to customers.
Additionally, there are less obvious factors and needs to consider, for
example:

Brand Image – Is the location consistent with the image you want to
maintain?
Competition – Are the businesses around you complementary or competing?
Local Labor Market – Does the area have potential employees? What will
their commute be like?
Plan for Future Growth – If you anticipate further growth, look for a
building that has extra space should you need it.
Proximity to Suppliers – They need to be able to find you easily as well.
Safety – Consider the crime rate. Will employees feel safe alone in the
building or walking to their vehicles?
Zoning Regulations – These determine whether you can conduct your type of
business in certain properties or locations. You can find out how property is
zoned by contacting your local planning agency.

A website is a must for a small business, if you don't have budget then you
can go for blogspot.com as it is free. Second step is to add your website ad
business in local listing of google which is also free. Once you do this you
will immediatly start receiving calls from clients.

If a business already has a cleaning company, getting them to change may be
difficult unless their current company is no longer providing good service.
Therefore, you may want to create flyers and distribute them to new
businesses. Also hand out the flyers in business complexes where you
currently have clients.

Have you thought of using your existing customer base and asking them for
referrals in exchange for maybe a free cleaning?
Do you have a budget? If not, social media (facebook), Google+ Pages and Yelp
can be a cheap way to get the word out.

When asking for the most "economical" way of finding clients, the most
relevant methods are cold calling and email marketing. Cold calling requires
no start up cost, you simply have to find the numbers of businesses near you
and start calling. Email marketing is also inexpensive as all you must do is
acquire the emails of decision makers in your area.

Promoting your business online through SEO requires the help of a
professional, as you must appear in the first page of google for your
selected keywords to appear to clients. If you are looking for help with this
aspect, feel free to click on the link in my signature below.

Hi there, check out the marketing section of our website. The following threads may also provide some helpful insight: http://www.sba.gov/community/discussion-boards/advertising-my-domestic-cleaning-business and http://www.sba.gov/community/discussion-boards/discuss-popular-topics/self-employed-home-based-business/trying-get-new-.