You started with a general value proposition about your startup's product or service. Now it's time to optimize it based on the why you've identified it in the step above and strengthen it with a booster.
These things work well against competitors who do not offer them. Boosters can be things like:
Think what small things you could add that wouldn't cost you much, but could be attractive to some buyers (these are the ideal elements to A/B test with your splash page). Make sure the booster is visible with the rest of the value proposition.
ExampleNotice the "free shipping" signs on the left and top right? Those are boosters.