It's been said that Clubs are no stronger that their members.
It is important to court new members who will bring revenue and provide staffing for your club. Generally speaking, new members don't step into a club management position the first year they join your club, but finding meaningful jobs that can be given to newer members can be really useful for your society.
Seniors and Retirees
Seniors may not move as fast, or be as up to date with technology, but oftentimes Seniors can provide valuable expertise and staffing to a club.
To be clear, I'm not talking about long-time hobbyists who have retired, but new-to-the hobby seniors. A retiree may only have one fish tank, but they often crave social interaction.
Go to where they gather in your community. Condos, hi-rises, Community Centers, etc. Usually the local newspaper will have a listing of their activities during the week. Give a talk at a local senior center or maybe set up a tank there. That will garner interest in the hobby. You may even find that some of those attending were hobbyists years ago.
When you have an event or show, a friently retiree is very welcome staff indeed.
Retirees have the time to spend and will enjoy helping your club in all activities. In other words, they are workers! Keep in mind that their budget may be severely limited. I have known them to bring their children and even grandchildren into the club.
College Students
If there is a college in your area, call the Biology Department to see if there is a graduate student or professor who works with fish. There usually is at least one person working with fish in every Biology Department. These highly educated people can be a source of new speakers for your club, too.
You can also arrange for permission to put up posters advertising the club. You'd be surprised how many students keep aquariums in their rooms and are interested in fish.
Army, Navy & Air Force Bases
Members of our armed services are often looking for a diversion and many also have a family with them. Many bases publish a local newspaper which is an excellent medium for your advertising.
You should attempt to contact some officer connected with personnel administration. It is a simple matter of phoning the base operator and asking for the number of someone from that department.
Some veterans suffer from PTSD and an aquarium can be a great way to help these service members.
Since Armed Forces folks move frequently, you club can be of service to these members by informing them of the nearest club to the place of their next posting or even providing them with a name or phone number of a hobbyist which would be of great help to them.