You could also use social signups. While this, like other sign in methods will need testing (on some tests conversion rates have zoomed when social sign in was removed) social sign up buttons (Facebook, Twitter, LinkedIn, Google) give people the comfort of familiarity.

And in case you need extra information (like address or telephone number) that the social sign up data does not provide you could always prompt users to complete their profile, the same manner that LinkedIn or PayPal does