I was a member of the Techshop maker-space here before it folded. The thing that did them in was a lack of casual accessibility, as well as an overambitious start, I think. The way they structured it was to charge large fees for "training" classes to clear you on the use of the various pieces of equipment, after which you were free to use them so long as you were a current member. But it would take several classes and hundreds of dollars to get even a small project off the ground, simply because of the way they mapped out the different class certifications. They were a business so it's expected, and the need for proper safety training is undeniable. But it meant that it took a serious investment before you could accomplish much, and those dedicated enough to do so would generally rather spend the money on their own tools. And on top of that they opened their doors with everything from CNC mills and 3D printers to automotive decal printers to SMB circuit board ovens to metal casting; in other words far more expensive equipment than their user-base actually needed or used.
At the end of the day, there are two things to strive for, and they wont be easy.
The first is variety of tools and workspaces. It needs to be a place where people come to tinker and to get some idea out of their heads and into reality. So it needs to offer access to whatever it is that the actual local users are wanting to use. If they want metalworking, get a welder and a few milling machines. If they want woodworking, get some drill presses and chop saws. But dont invest it the cutting edge of everything up front. I recommend some kind of request system, so it can organically grow in the directions the users want. If they see the space is responsive to what they feel they are lacking, it will also go a long way to keeping them coming back, even if they dont have every little thing at first. This will be a balancing game between responsive acquisition and responsible budgeting. Fundraising drives can help, just like a high school that needs a new scoreboard, etc.
The second is casual Accessibility. Dont make them spend a hundred bucks and take a class that won't be held again for two weeks, just so they can drill a single hole. This is another balancing act between responsible safety and easy access, and the first solution is staff.
It also really helps to have a large scrap pile for free (or free-ish) materials.