4
My suggestions
1.To learn more about the phonetic features of the target language (i.e., English) and of the first language (e.g., Mandarin) in a systematic way and find the contrastive mechanism that governs the pronunciation of both languages;
2.
2.To explore the fundamental phonetic “phenomena” of both languages;
3.
3.To be aware of  how and when pronunciation should be taught/brought in during instruction;
4.
4.Always remember that nothing is absolute in language instruction.  A “good” instructor is to be able to help learners recognize different values of a language, rather than to exclude different accents of a language.