In this difficult economy we are all trying to come up with low cost, effective ways to reach new customers.  As marketing continues to change, there are a few things that remain constant.  In the words of guerrilla marketing expert Jay Levinson:

Commitment - “A mediocre marketing program with commitment will always prove more profitable than a brilliant marketing program without commitment." 

What he is saying is that you need to keep that top of the mind awareness and be patient!  The first time a person sees your sign or promo they don't see it.  The second time s/he doesn't notice it, the third time s/he is conscience of its existence.  It takes at least twenty times for the person to make a decision to buy. 

Investment -”Marketing is not an expense, but an investment - the best investment available in business if you do it right."

One thing about signage, it costs about 10% that of broad-based media such as TV, newspapers, radio and yellow pages.  Also other media stops as soon as you quit paying for it.  Remember the patience/commitment factor!  Signage is your silent salesperson.