The use of Builder classes can simplify the interaction between Kotlin and Java by providing a clear way for users to build objects step-by-step, making the code more readable and reducing the likelihood of mix-ups. Default arguments on methods can be used to make functions more convenient for Java developers, while @JvmOverloads can generate multiple versions of a function for each combination of parameters. Companion verbosity in Kotlin can be avoided by using @JvmStatic or @JvmField annotations, which allow for more direct access to static fields and functions from Java. Specifying where checked exceptions are thrown is essential when calling Kotlin APIs from Java, as Kotlin does not share this concept with Java. Finally, generating default interface methods for Java interfaces can help bridge the gap between Kotlin and Java, while avoiding internal visibility modifier in API design is recommended to prevent accidental usage.