Flattening Rust’s learning curve

I seem to have eased into a rust programming style that dodges these, perhaps at the cost of some optimizations. Using the first example, for example (The article suggests this): Don't return an `&str`; use those for transient things only like function parameters; not for struct fields or returned types.

I'm starting to wonder what I'm missing out by doing this. Not addressed in the article: Any tips for using the more abstract features, like Cow etc? I hit a problem with this today, where a lib used Cow<&str> instead of String, and the lifetime errors bubbled up into my code.

edit: I found this amusing about the article: They demo `String` as a param, and `&str` as a return type for triggering errors; you can dodge these errors simply by doing the opposite!