In the beginning, we give general advice, which is the most important thing, by reading books that strengthen you in the language and also solving problems a lot gradually
1- Atomic Kotlin ==> https://www.atomickotlin.com/atomickotlin/
2- Head First Kotlin ==> https://www.pdfdrive.com/head-first-kotlin-e196919920.html
3- Kotlin Apprentice ==> https://www.raywenderlich.com/books/kotlin-apprentice/v3.0
1- LeetCode ==> https://interview.leetcode.com/
2- HackerRank ==> https://www.hackerrank.com/