In other words, instead of Sign Up now! consider a call to action such as Create your first invoice Now! or Write your first post now! or something else.
The idea, simply put , is to drop visitors straight into the deep end. Enable them to do something as quickly as possible. Let them splash around for a bit before being asked to commit. This gives the visitor the freedom to experiment with the application, easing the pain of handing over his email address to create yet another account on yet another site.