I want to start a cleaning services business and I want to know how promote it in the Internet ( free is better for me) thanks.
Since - I'm assuming - you're going to have an actual physical address, you can start by submitting your info to Google places and maps. Then you can submit to online yellow pages...
Even if a business is an "offline" entity it should still have a website. Even local businesses should. People turn to the Internet before the yellow pages, any offline business would benefit from a website IMO.
Oh I misread the question. As others said, use the various online resources that first come to mind. Create a web site, submit your data to the Yellow Pages, find local community sites and see if you're allowed to submit it there (e,g there may be Forums based on your local town). I wouldn't say to use social networking sites for this though, that just sounds stupid. If it works, then fair enough, but I can't see it being too successful. I do know of some businesses that promote stuff using social networking, but the fact is that virtually all of the people they are marketing to, are return customers anyway, if anything they'll be slightly losing out from all the discounts etc.
A website would be a place for your customers to go to for information. It could contain your address, phone numbers, names, and other contact informations. Websites work well to be a good page of all your information a customer may need. Thus, if you post your services in classifieds or in Yellow Pages, you can leave your website URL there. Local community pages or bulletins can also show your website there.
What most people use: SEO, Google advertising, Facebook ads, blogs. You can also try: viral contests, refer a friend programs. I would not bother with forums unless you have a forum within your city.
I would focus on localized search. Listings in classifieds, optimize for your specific region, participate in forums related to your niche etc...
This is an area that I specialise in. Firstly you need to get a website up and running which is search engine friendly, it only needs to be relatively simple. Next you need to get your site listed on Google Maps and the other main online directories. You now need to make a relative Facebook, Facebook fan page and twitter page and add people who are targeted to your business either manually or using a tool. Next you need to use several free advertising methods to drive targeted local traffic to you website, this along with SEO. I understand it sounds a lot but this will make a MASSIVE difference to your business for only a small outlay. If you need anymore advice or have any questions send me a PM. I also offer a relative service.
Free Classifield sites like Craiglist and many others. I think it is most effective free way to advertisie your offer. I can share with you 300 list of free classifieds sites, just pm me and I will give you these sources I use for my business
Join your local forums. Most of the times they allow you to post your ad. Volunteer. Sponsor. Involve. Start your SEO campaign if you have your own website. Circulate some mailers.
Local facebook advertising is very good for that matter and it's done by targeting people living in the area of the offline business.