Visit all of the similar sites you can find. Make a list of what works for them and what looks just plain sad. This, more than anything, will help you to codify in your mind what your site needs to look and function like. The unique mission of your site will determine its content. These are all questions you have to answer for yourself before you begin developing your web presence.
Many organizations start with the minimum necessary to maintain a presence.
These sites can be free. Often they are maintained by a member as part of their organizational duties. In next to no time you can have a single page on the web for free. The advantages to this are obvious, the site is free, there is very little time consuming maintenance, and the mission of the site can be fulfilled if it is one that is limited. The disadvantages are not so obvious.