Just like a new orchid plant initially requires special care, so do new society members. They need to be given gentle guidance and assistance at every turn to help them to achieve success with the culture of their plants, while giving them the experience that they will be able to rely on in future years. Freely share knowledge and experiences with them to cultivate their growth. Explain why something they're doing is wrong, don't just say that's the way it is. This will help them to understand their plants better, as they work their way towards their own success stories.
If you have beginner groups in your society, then make sure the leaders of these groups are good and knowledgeable growers themselves. I know that it's hard to get volunteers in a society, but be discriminating ! Remember that these groups are the source of your future active membership. Just as you would not want someone off the street teaching your children, so you should be selective of who is teaching your new members. At a recent Nursery workshop I held, a new member of a local society shared that he had learned more in two of these workshops (totalling 40 minutes) than he had in an entire year at his local society. Although this made me feel good about the workshops, it was disappointing that he felt so disatisfied with his own society.
Try to acquire the best and most knowledgeable speakers for your society that you can afford. This will nourish the knowledge-base of new members and spark renewed enthusiasm in your established membership. There is nothing that will squash budding enthusiasm as quickly as a bad and/or boring speaker.