Our homebrew club is pretty young, and I wasn't there at the beginning. But I have been in it for a year and am one of the more active members. Monthly meetings are important. We have ours the same time each month at the same place. We recently added more structure to which homebrew styles people should bring to each meeting. For example, October beer styles:APA, Am. & Eng. IPA, IIPA (DIPA), Am. Amber, Belgians, Meads & Cider
We found people were just getting really drunk instead of learning something or getting familiar with specific styles. The president is going to start giving 10-15 minute lectures about technical issues with accompanying handouts.
AHA events can be a big help to interest potential members such as Big Brew Day and Teach a Friend to Homebrew Day. We usually have two potlucks a year, an Octoberfest in September and a Hair of the Dog New Years party in place of the regular January meeting.
One thing I wish our club did more often is get together to brew. My rig is quite portable, but we are spread out pretty far across north central Indiana and south central Michigan. We are in the process of having our second competition (in-club). Everyone brews the same recipe and then we compare and see who produced the best product. Kind of a neat take on a competition I guess.
We have done one bus trip to 4 michigan breweries including bell's, and are planning another I believe.
Just some ideas for you. But to get established, make a website, hold regular meetings, leaflet the pubs and LHBS in your area. Get some friends to come, even if they only have a small interest in brewing.