Post cards can be very effective, but do not look past the potential effectiveness of direct mail. Direct mail, if put together properly, can get any message you desire directly in front of the audience you want to receive that message. A well written letter, with a call to action, written with a personal touch, on a professional letterhead, in an envelope with company logo on it, with a business card inside, hand addressed, with a first class stamp, signed personally, and addressed personally will out perform any other method of marketing out there. If you are precise with who you want to target and follow the steps above you will weed out on your own the people not interested in your service. Your letter will stand out versus the flyers, door hangers, post cards, etc.... People will take you seriously because they feel you are a professional outfit willing to take the time to separate yourself from all others. A closing rate on post cards, if you are lucky, could be 1%-3%. But an effective direct mail campaign could result in a 14%-18% closing rate. Although it was several years ago, I built my business from 45 accounts (maintenance primarily) one year, to over 130 accounts the next - most being full service high end clients. I sent 2,500 letters which cost me about 50 cents each and I received over 400 phone calls. It was one of the most joyous and painful experiences all wrapped into one. I built my business with high quality accounts which explains the joy, but I also had to turn away a significant number of potential clients as well - all because of direct mail. For the next 7 years I continued to utilize direct mail to the point where every single client I had fit the exact profile I wanted - willing to spend money for a professional service.