So many cards and fliers out there kind of look the same and people are used to it.
You need to make it different, call to action, deadline and most important...........
A reason to call you, that is the hardest part.
Most things out there are like blah, blah, blah, call for prices, call for a free estimate, call for a free proposal, call for a free blah, blah, blah. Those are not reasons that would make anyone call.
Most designers are not experts in marketing, even though they can design great looking cards, make them look pretty and get people to look at them for a few seconds before throwing them away but that usually does not get the phone to ring.
Listen to Ant, he really knows his stuff!
This is the kind of info that you either learn (long time learning, lots of investment in books, dvd's, seminars around the country, etc....) or pay someone to do for you then and only then take the info and have the card put together and do testing on them, not bulk mailings because you need to see if it works, if not then redesign it until it does work. Then do larger mailings when they are working for you.
This is not meant to be mean or rude but the card would not make me want to call so it needs work before mailing out a lot of them.
Good Luck.