Wow, you ask a loaded question.
Our club has been around for 10 years, but I believe it has really taken off due in small part to my efforts. We set up a message board, and I pretty much pleaded with our members to start using it at every meeting each month. Once the gang started posting to one another, some close-knit bonds were formed between the members and they really started to look out for each other. We also tend to do a lot of group buys, almost monthly.
We also make it a point to build a good relationship with our LFS rather than constantly tearing them down. Mail order is great, but imho you need local fish stores to get things now. Plus, I never buy any livestock via mail order. I want to see it, study it, buy it and get it in my tank within the hour. I don't want to pay box fees, overnight shipping fees, and pray FedEx / UPS doesn't screw up, and still risk it that the animal doesn't survive. I only buy locally, and appreciate that we have so many LFS in our area:
http://www.melevsreef.com/lfs.html
We have two Frag Swaps a year. Yesterday was one of them, and I swear 200 people showed up for the first hour.
http://dfwmas.com/newsletters_html_format/2004Dec/DFWMAS_dec04.html
We have at least two Tank Tours a year, where we spend the day visiting six tanks in a particular area of the metroplex.
http://www.sparklingfloorservice.com/melevsreef/dfwmas/tt/feb05_tanktour.html
We had a Coral Propagation Workshop last October, with 85 people attending and 65 participating.
We had our Next Wave conference a couple of months ago, and flew in four speakers for one day, and everyone that attended benefitted greatly from the knowledge they gained.
http://www.dfwmas.com/next_wave/2005/nextwave_images.html
We also have a Winter Social each December, where we have a sit down dinner and raffle for the members. Last year, Roger from Tunze, Inc came to speak to the club. There are a few images in our newsletter.
http://dfwmas.com/newsletters_html_format/2005Jan/DFWMAS_jan05.html
We have monthly meetings, and these move around the metroplex, sometimes in homes but mostly in the LFS that offer. With about 80 people showing up each meeting, we have to have room for the bodies, and the cars. Every meeting ends with a raffle, where members and guests can win livestock.
And as you can see, we have a newsletter that I do my best to get done monthly if at all possible.
Does this mean you have to do all this, and more? No! Our club has grown over time, and with the energy and help of several dedicated hobbyists, we have a great club. We've added more and more events to make it better, which makes the workload even heavier. You will have growing pains as you organize your group, and have to simply roll with the punches at first as you grow and evolve. In the next MASNA newsletter, I hope to include an article about how to start a new club. In the meantime, go to MASNA.org for more information about how you can begin getting organized.
I hope this wasn't too overwhelming.