The next step is to convert your existing Java files to Kotlin files. You can do this manually, or use the automated conversion tool provided by the Kotlin plugin. This tool will generate Kotlin code from your Java code, while attempting to preserve the logic and formatting as much as possible. However, the tool is not perfect, so you will need to review and refactor the generated code in order to make it more idiomatic and efficient. To improve your conversion process, you can convert one file or module at a time and test the functionality and performance before moving on to the next one. Additionally, you should use annotations such as @JvmName and @JvmStatic, as well as modifiers like lateinit and lazy delegate. You should also use when expressions, range operators, and functions like apply, run, let, with, and also. Doing so will help you avoid name clashes between Kotlin and Java methods or properties, enable default methods for interfaces in Java 8 or higher, avoid wildcard types in generic parameters when calling Kotlin from Java, declare checked exceptions in Kotlin for Java compatibility, initialize properties that are not null but are assigned later, initialize properties that are expensive or depend on other properties, delegate properties or methods to another object or interface, replace switch statements or complex if-else chains, check if a value is within a range or a collection, and perform operations on objects or values in a concise way.