Fine tuning my pronunciation

I've talked to about 10 native speakers now, 2 in real life and the rest on skype. Every one has been very surprised initially that they can understand me, or that I actually start out speaking Mandarin, or something. I guess there must be a lot of skype users who aren't too interested in good pronunciation. Anyway, after starting out really well, one guy burst my bubble the other day by not understanding a particular word I said.

It turns out while using Pimsleur I've been ignoring the differences between x and sh in some words for the sake of speed. Tsk tsk. Now this has carried over into my conversation, so I'm beating it back down. I'm being anal about this specific pronunciation, and I think I've got it licked now. But this got me thinking, it's time to review pronunciation again.

Reviewing pronunciation makes a lot sense. I now believe it's an iterative process. I did a big pronunciation pre-study to begin this journey, but I didn't try to perfect it, thinking it would be far more efficient to let the minor details work themselves out. And this has worked for the most part. But I've noticed some nagging little differences too, and I can't remember my training in every instance.

So I'll review now, but I have decided to try a different source. Getting complete pronunciation explanations from several different sources makes a lot of sense to me. There are advantages and disadvantages to most sources, so why not use them all? Of course, time is an issue. I wouldn't finish 2 complete beginners texts which cover the same material, for example, due to the amount of time required. But pronunciation explanations/drills can usually be completed in a few hours, so here we go.

I've begun using the first module of FSI Chinese. It's free, and is a very comprehensive unit from what I can tell. There are 6 "tapes", all 20 something minutes long. There is a PDF to stare at while the tape plays. It's free; I downloaded the PDF, but not the tapes. I just play them online.

Wow, I'm glad I decided to do this. they point out all sorts of little things I didn't know, or wasn't paying attention to before. I can't wait to get to the last tape, which covers mixed tones. I've been ignoring the differences between 3-2 & 2-2 tone words. Many sources tell you to pronounce a 3-2 as a 2-2, which is obviously wrong. Others tell you to pronounce a 3-2 as "half of a 3"-2. I've heard this is not quite right either. I can't wait to see how FSI handles it.