Without additional context of what you're trying to build: talk face-to-face with people and stand over their shoulder as you walk them through the signup/first

Without additional context of what you're trying to build: talk face-to-face with people and stand over their shoulder as you walk them through the signup/first use process. Though neither sufficient nor strictly necessary, willingness to pound pavement for your first users appears be highly correlated with traction. It's the quickest way to find out how people will actually play with your product.