Yue Nagareboshi link said:
You can learn a lot by testing.
Also watching other people's ways is useful to make your own.
Recently there was an event at NND that was meant to make others learn how to pitchbend by showing your methods on a video. You can look for these videos under this tag: 調声æã大ä¼2012
Hope these videos are useful for you.
I recommend this too, it's great to see how different pitchbend methods work. All kinds of users, overseas and JP alike, took part in that owo
Personally, I learn from finding USTs that have nice tuning and studying what those do. It's a great way to learn some basic ideas of how to tune for the sound you want. From there it's a lot of experimentation... everyone has their own style, and every song/bank has its own style, too. That's what would make a formal tutorial difficult...
My personal "rules of thumb" are these: pitchbends from above add strain, pitchbends from below add dynamic. Vibrato goes on long and high notes, and other notes depending on what style you're doing... vibrato is a great tool, but you have to use it carefully.