Based on what I’ve seen, your town is going to need some sort of industry. Whether that’s some kind of educational institution, military base, industrial facility, or something else, I don’t know. But it seems like I haven’t seen a middling-sized town that doesn’t have one of those. And it seems like all the small towns I’ve seen do not have those sorts of things.
I would say that if you’re close enough to a large city, you position your small town as a commuter city- you give yourself a cute downtown by cleaning it up, giving economic breaks to local high-ish end restaurants and other nifty shops, and set it up as a sort of quaint mini-entertainment district. You’ll also want to make the area around the town attractive for developers, however you accomplish that. And get your town on the local commuter trains, etc… The idea would be to attract new (wealthy) residents through having relatively inexpensive new homes, and have them drive into the city for work, but spend their leisure time in YOUR town in your downtown area, and even possibly attract the big city types for that kind of thing.
If you’re in some kind of small town 100 miles from nowhere, like say Hamilton, TX, then I’m at a loss. You’d have to have a pretty impressive tourist attraction to get people to drive 2.5 hours from Dallas, or 1 hour from Waco to go to it, and in the absence of some sort of local industry/military/educational institution, I think the town will be destined to remain small.