Users who continually find value in a product are more likely to tell their friends about it.

When designers intentionally trick users into inviting friends or blasting a message to their social networks, they may see some initial growth, but it comes at the expense of users' goodwill and trust. When people discover they've been duped, they vent their frustration and stop using the product.

The aim is to influence customers to use your product on their own, again and again without relying on overt calls to action such as ads or promotions.

Products with higher user engagement have the potential to grow faster than their rivals.

For an infrequent action to become a habit, the user must perceive a high degree of utility, either from gaining pleasure or avoiding pain.

Brainstorm new interfaces that could introduce opportunities or threats to your business.

Many innovations fail because consumers irrationally overvalue the old while companies irrationally overvalue the new.