People always think that bigger is always better. So there is an obsession with facebook likes and shares. How many people like your page or how many people like your posts. Likes and shares should be used to judge what people like from your posts. So see what people like and give them more of the same. See what types of posts people do not like, and stop giving them those things. You are better off with 5000 users who are enthusiastic about what you are offering as oppposed to 50,000 users which are luke warm. These 5000 users will help you gain like minded followers. Often as groups grow bigger, they start to lose their quality and direction. If you take care of the little things you won't have to worry about the big things they will take care of themselves. Niches are more important then something that is general and broad. So you are better off to have a group that deals with a certain breed of dog as opposed to a group that talks about dogs in general. Quality might be a slower way to grow things but it pays off in the long run.