Got my first 200 at Wii bowling: 214, in the middle of a 594 series (199-214-181). Pretty close to my real-life best (636), and I had some of the same feelings: elevated heart rate, propensity to choke (left a 6-pin in the tenth frame of game 1), although I fought through it nicely in game 2.
In the process, I discovered that when you're a Pro, you get a cool ball, kind of sparkly with stars on it. It makes it a bit easier to pick up the spin on the ball, although I wish they'd use a line or something like that.
What helped was that I did a bit of practice first, the power bowling. Now if only they had some form of shadow bowling ...
I did notice that they are not superstitious. They don't wait for you to finish the string to add up your score: I started off with a four-bagger, and sure enough, in the third frame, it posted that ugly 30. (Hey, I'm not really superstitious, but some things you just don't mess with.)