What are best practices for registration process?

I'm designing an mobile app. There are 4 input fields that users must fill all to complete the registration. Those are full name, email address, password and username. First, I thought placing all in one screen might give users a simple registration experience, but later it looked scary to see too many fields in one screen. Should I divide all fields to steps provided that each field will be in one screen? Or, there is a common practice for the registration process?