My wife and I have been studying Chinese casually for a couple of years now and I have been using Chinese Pod for almost a year.  It is very slow going, but I plan on keeping at it. 

I liked the elementary lesson, "The Panda's Secret Wish" and worked on it for the last week until I could say it to a Chinese co-worker.  The roughest spots were that she could not understand "yuan" of "yuan wang" (wish) and "cai" of "cai se" (color).  It was extremely frustrating as I tried to repeat each of these from her corrections but never got them right.  I cannot understand from her explanations what I am doing incorrectly.  The "yuan" seems to be the oo sound and not the inflection, which I'm pretty sure I'm getting right.  The "cai" she says sounds too much like "zai".  I am thinking "ts" and it sounds to me like I'm softer than "dz" but obviously I'm not getting it.

Any specific help on pronouncing these two words would be much appreciated and if there are resources for just getting better at pronouncing words, I would also appreciate that.