Opportunities to interact should be obvious. People should not have to guess or look for opportunities to interact.
When developing interactive media, users should have the ability to review an interface and easily identify where they can interact.
Make it a habit to provide hints and indicators. More like, visual cues such as buttons, icons, textures, textiles, etc.
Allow for the user to see that these visual cues can actually be clicked or tapped with their fingers, for example.
We should always take into consideration the usability and accessibility of our interactive media and how the user sees and perceives the objects in the interface. There are very few situations where ambiguity is helpful when it comes to perceiving the ability to interact with something.