Answer : There's no one-size-fits-all answer to this question, as the best way to learn interior design will vary depending on your individual strengths and weaknesses. However, I generally think that SketchUp is a great tool for learning interior design, as it allows you to easily experiment with different design concepts and see how they look in real life.
That being said, it's important to also supplement your use of SketchUp with other forms of training, such as reading books or magazines about interior design, attending workshops or webinars, or working with an interior designer mentor. By doing so, you'll ensure that you learn all the different aspects of interior design and become a well-rounded designer.