Direct mail campaigns are one of the top real estate farming ideas for agents. The document discusses how to choose a farm area and effectively market to that neighborhood through various techniques. It recommends identifying a farm of 250-500 homes and developing a detailed marketing plan. Successful farming involves diversifying marketing methods like email campaigns, contacting FSBO and expired listings, door knocking, telephone calls, holding block parties and open houses, creating a neighborhood website, using social media, and implementing direct mail campaigns on a regular basis to continuously contact residents and position oneself as the area expert. Measuring the success of these various farming strategies helps determine if it's time to invest further in a neighborhood or choose a new farm.