Loads of guys have said it already, but here goes, AVOID GROUPON! all the reasons are above.
Something I do regularly, but is a great way to use your time if quiet, is start to build relationships with people who might refer you. It's what Howard Partridge calls "Doughnut Friday". Buy some bags of doughnuts in Sainbury's, and put a sticker on them and take them to carpet and upholstery retailers. The sticker should just say something like "Thanks for recommending us recently, it's appreciated. Put the kettle on and enjoy these with our compliments. All at XYZ Cleaning" DO NOT put a telephone number or web address on, it's not an advert it's a thank you, and you'll be asked for some cards anyway. I did write a blog article about this on our software website, but here goes...
Walk into the shop and ask for the owner/manager, even better if you know their name before hand. Just say "I was just passing and wanted to drop these in as a small thank you for recommending us recently. I don';t know who it was here but a client told us someone here had recommended us." Pass the doughnuts and smile and say nothing. They always thank you for them but also it starts the conversation along the lines of "oh yes we know about you" or whatever, but it's a soft foot in the door that ask them to start recommending you, by assuming they already have and rewarding them for it. Just try it, they will ALWAYS ask for cards, which you just happen to be able to find in your poaket after a little bit of a search

Then just drop in again in 6-8 weeks aain. We have loads of retailers recommending us from this simple approach. This also works with Estate Agents etc.
This uses your quiet time to build the relationships and start the steady stream of referrals coming through. Beware though, you will be drinking a lot of tea, and eating a lot of doughnuts with them

Remember to make sure you record somehow who they have recommended when they do start recommending you, if you can go back in and mention Names of people who they have recommended they will be delighted

Al.