There is no point building a skyscraper to house five people. It is far better to start off small and build new floors as and when they are needed. Forums are no different.
I am sure many of you have come across forums that have so many categories you just do not know where to start! A lot of online communities are not subject specific; they are communities where conversations include all kinds of different subjects. As a result, many of these communities try to categorise almost every subject of human thought! This is a big mistake when starting out a community.
It is very easy to get carried away with a new forum site, and setup categories for all manner of subjects in order to try to cater for every visitor. Unfortunately this has the negative effect of making your forum look even more empty and overwhelm your users – both new and old.
I would always recommend starting off with just a few separate categories. This makes your forum easy to understand, and concentrates posts within these categories. It is far better to see a new forum with a good number of posts in four categories compared to seeing a forum with seventy-five categories and only a few posts in five or six of them.
As your community grows, you can then set up new categories and move existing posts that are relevant to the new category there. Not only are you then expanding the number of categories at a pace your users can keep up with, you also have ready made content for each of the new categories!
It is very easy to get carried away when starting a forum. Once again it helps to always get into the mindset of a visitor to your site. They want simplicity and intuitiveness. New members do not want to have to struggle to figure out the most relevant category for a potential new post. Visitors do not want to see loads of categories without posts. Keep it simple and expand only when your community is ready.