I've recently read Principles by Ray Dalio. Can you suggest me another book on the same topic?
Here is one book similar to Principles by Ray Dalio:

Atomic Habits: An Easy & Proven Way to Build Good Habits & Break Bad Ones by James Clear

This book deals with self-improvement, success, and personal growth, which are central themes of Principles: Life and Work.
Atomic Habits seems a bit too casual. Could you suggest something by someone else who is incredibly successful?
Sure, here are some suggestions for books on habits and personal development by highly successful individuals:

The 7 Habits of Highly Effective People by Stephen Covey - This classic self-help book has sold over 25 million copies worldwide and has been endorsed by numerous successful leaders.

The Power of Habit by Charles Duhigg - This book explores the science behind habits and how they can be changed to improve one's life. It has been praised by figures such as Bill Gates and David Allen.

High Performance Habits by Brendon Burchard - Burchard is a highly successful personal development trainer and coach, and this book distills the habits and practices of high-performing individuals.

Atomic Habits by James Clear - While this book may be more casual in tone, it has received high praise from successful individuals such as Mark Manson, Tim Ferriss, and Ryan Holiday.

All of these books offer valuable insights and strategies for developing effective habits and improving oneself.