Add elements of scarcity and impatience to your product.
Scarcity and impatience are dark hat gamification strategies, but used correctly, they can be very powerful. You can observe that these elements are used in almost all popular products. Facebook was limited to only Harvard students at the beginning, Twitter has a limit of 280 characters, and many modern mobile games can be played for only 30 minutes before you have to wait for more lives.
Simply stated, if a user can do everything without limitation, they will become bored very quickly. Adding more limits will add more fun.
Use anchored juxtapositions to maximize the monetization.
Always give two options to your user: the payment or a set of a desired actions. The desired actions can be very difficult but possible to do. Take an example from Dropbox: you either pay for more space, or you can invite your friends.
Make the desired actions limited to the user. A user can do only a certain amount of desired actions.
For example, on average, a user will select more hobbies if they can only select five of them.
Add elements to your product that can be accessed only at a specific time.
For example, make a promotion available only between 12 and 1 p.m.
Make the user wait for more.
Don’t give the user everything right away. Instead, limit some options so they have to wait. Here, you can monetize additionally if the user would prefer to pay instead of waiting. For example, in Candy Crush, you have lives, and when you die you have to either wait 25 minutes, ask a friend for a life, or pay.
Make an evolving user interface.
At the beginning, do not show the user too many options. Make it simple. But over time, you can show more and more options.