Spend $10-$30/day on Google Adwords for a couple of days just to get early adopters.
Google Adwords is an advertising service that delivers advertisements corrseponding to the keywords that users search for. For example, if a lot of user searches for "how to start a startup", it would make sense for StartitUp to use "start a startup" or "how to start a startup" as a targeting keyword. You can use the keywords you have found before, and see which ones are not very heavily targeted by other competitors (which means to cheaper cost per click).
In short, you will want to use Google Keywords and discover keywords:
1. that a lot of people are searching for - local searches/global searches.
2. that have "Competition" as "Low"
3. has low CPC (cost per click)
Remember to group different category of keywords into different groups, as the total CTR (click through rate) of a group of keywords will affect the cost per click. The reason is because Google likes to see that your ads are relevant, and their users are finding your ads useful. Therefore, the more effective your ads are, they will charge you less, because it helps them too. Vice versa, if they do not perform well, they will charge you more, or penalize you more, for creating ads that are not relevant.
While this is not necessary, it does help you get some spare users to test out your service. Google Adwords is a very difficult discipline to master if you have not learned about it. A good place to start would be here:
A good advertisement header is just like your UVP. The sub-header should have other benefits and a call-to-action, like:
Header: Learn to be like Mark Zuckerberg
Sub-header: Build a successful startup in 30 days. Get your free trial now!
Also see how to write a great adwords ad: