One of the most impactful strategies you can set up in your application flow is to provide the user with some common UI elements throughout the application, no matter what state the application is in. Think about some borders or some graphic elements acting as branding for the general look and feel of the app. The actual content may change but the frame, that is, around the main spot, may be the same and lets the user stay in a familiar environment all the time. This way, the user will feel at home all the time and will be more prone to focus on the actual content as it is the thing that really changes before their eyes.
The same is true for transitions across views, that is, if you provide the user with a way to go from state A to state B (meaning the transition is allowed), then you implement the transition using an animation (possibly meaningful). It would be very convenient to keep the same convention when going from state B to state C. Obviously...