Actually I think it is crucial to: a) put a really interesting headline, b) additionally: list 1-3 top features that establish and differentiate your service/pr

Actually I think it is crucial to: a) put a really interesting headline, b) additionally: list 1-3 top features that establish and differentiate your service/product, c) put a "leave your e-mail" text box with dummy "your@email.com" content so that there is no doubt it is to leave your e-mail, d) ensure there is no more text on the page besides the above, so the page as a whole is tidy, nice and clean. And don't afraid of using large fonts.