New Concept English is a good set of teaching materials, which is often used in teacher-assisted training, but it is not the best teaching material for self-study.

Language learning includes two parts: input and output. Learners input the target language through the materials provided by the textbook, master the language and output ideas through after-class exercises. Self-study should follow this principle.

I suggest you use practical English, which was published in China after FLTRP imported copyright from the United States. Courses are written according to themes, and each theme trains learners to master vocabulary and sentence expressions related to the theme through listening, speaking, reading and writing activities. In this book, the author combines input activities with output activities well, so that the learning process can achieve the purpose of applying what he has learned.

In addition, the 15-day Fast Training of Emergency Spoken English-Business Chapter published by Xi Jiaotong University Press is also a good little book with mp3. You can use this book to improve your spoken English, and pay special attention to the training methods in the book.

I have used both of them and find them very efficient and effective. I hereby recommend it. Have fun studying!