Which tools have a great signup process? (incl. Tour)
I'm a fan of uxarchive for inspiration: http://uxarchive.com/tasks/signing_up
This is great!
Have you seen this one already? http://www.creative-tim.com/product/login-and-register-modal
I think that the best way to design a Singup Form is to go to some of the most well-known websites which has a form (such as social networks and online schools) and see some semblances between them.
You can check useronboard.com for some great examples. Process depends on business needs and user goals.