Why do you use Pinterest? For some, they love the feeling of having others like and share what they post. For others, though, people use Pinterest as an organisational tool. They pin their recipes, favourite vacation destinations, etc. They also use it to find out what’s in style or what the hottest deals are.
If you scrutinise these uses, you will see that Pinterest has evolved into a search engine. Therefore, your strategy to pin should be centred around that fact. Treat Pinterest as if it were a search engine.