The "la la" trick for tone/pronun'
I don't know if this will be useful for you...but it helped me.
My Vietnamese teacher taught me a neat little trick that has helped in my speaking and pronunciation:
Before I say any word or sentence I repeat the sound "la la" to myself (you know, like the music note doe, ray, me, fa etc...)....this gives me my FLAT tone and and gives me something to base all my raising, dipping etc tones off of.
Ooops, I don't think I've explained myself very clearly!