It should be uncluttered, organized to emphasize the message, be attractive and easy to read. Put a boarder around the ad, so that the eye stays focused on your copy. It should be logical, acceptable to the audience, and it should support the message. A business type picture of you is most appropriate. It creates trust.
Classified ads are economical, as they can be run frequently.
Remember, flyers and business cards are also advertising. In advertising, the rule of thumb is three. Three times is a minimum. Spaced repetition is how we learn and why ads pay off. In fact, the ad should run often enough to push the message into the reader's consciousness.