As with any business you need to monitor where your enquiries come from. Everyntime someone rings up for a quote, ask them how they heard of you. Write it down, then you will know which methods work for you and which don't.
I use Yellow Pages, have done for years and it always brings in far more work than the advert costs, even though I live on the border between two directories. But this isn't my only way of advertising, I also use the local parish magazines, about 10 of them
The mags vary enormously in price, so I'm very careful to monitor them so I know which ones are cost effective. I also have an ongoing leaftlet drop, just a few each week (keeps the wife busy for a couple of hours
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Marketing is like everthing else - don't put all your eggs in one basket.
Don't rely on a big flashy Yellow Pages ad to bring in the work you want - do a modest 2 or 3 column centimetre ad in a box and spent the rest of your budget on other ways.