Does anyone have suggestions relating to up-selling premium features.
I'm specifically interested in hearing thoughts on balancing the need to make the premium feature discoverable and the need to make sure that users don't get annoyed by the premium-feature ad within their app.
I'm looking for generic guidelines. So it doesn't matter whether you have experience relating to premium features on a "free" website or in-app purchase features in an iPhone app or premium features in some other platform.(Of course, examples from any particular platform will be welcome)
Experience (as a developer) selling premium features will be valuable. Experience as a user who has seen premium feature ads will also be useful.
