When you think or hear a particularly clever phrase, write it down. Whenever you feel the creative urge, stop all other things and write it down.
When writing, try to imagine and feel what it is you are talking about, and metaphors will naturally suggest themselves from a combination of embodiment of feeling and resonance against the words you have already written. For each of the lines you noted above, can you feel how the author feels and thinks about the item being discussed?
Particularly potent writing uses this device, lingering on these interwoven metaphors to set a contextual feel that makes it easier for you to get the point they intend for you. In this example, the first three are interwoven metaphors all drawn from the schoolyard.