I would just go with a typical signup process. Don't listen to all the growth hacking stuff when you're first starting out. If your service is good, people will use it. Period.
Optimizing for bounce rate comes after. I see so many people fall into this trap because they read too many growth hack stuff online. These are all correct once you get to certain point, but when you're just starting out they're nothing more than distraction.
I've been there, and learned the hard way that optimizing early is not only unproductive but actually counter-productive because:
1. Let's say your optimization effort paid off and 100 more people signed up. This only means you had a good optimization strategy and doesn't tell if your service itself is attractive or not. Which means you may feel like you have made some progress but you actually haven't. Let the product speak for itself.
2. From my experience, if you have a compelling product and just put some effort to put it out there and promote, you WILL get users.
Optimization by definition is something you do when something's already "working". You have no idea if your product works or not early on. Your goal is to find THAT out.