Thanks for the comments, Beijing No.2 #. They are different from my thoughts and I appreciate them.
Here are what I thought about practices and they are open to discussion.
1. Muscles. During my training, my tutor said "speak as slowly as possible to build up the muscles". A lot of time, I think I pronounced with the right way, the sound was still weird because of the weak muscles. When the muscles are strong enough, the sound would become natural when the right pronunciation is unconscious. Thats the reason that I want to exaggerate every vowel and word to let my muscles remember the behaviors. I agreed what Xiao Qian's said " When the pronunciation is right ( sound and stress), the intonation will eventually come naturally".
2.Mouth and Ears. I totally agreed that both need to be trained. Actually, NCE reading is a good way to train the ears and practice the mouth. The reason my teacher said "Trust your mouth but not your ear" is that, at the first beginning, it is difficult for a newbie to tell the difference between the correct and wrong one especially the mouth positions are similar. But I will not make a big mistake when I watch your mouth. I felt my ears became more acute and I am more aware about people's pronunciation after I read NCE. The mouth movement seems helping ears too.
Thanks again to point those out and set a high expectation on me. I would love working on the challenges.
Thanks.