To improve at Darts start a game against the CPU and choose Standard Cricket. The only parts on the board that count are 15, 16, 17, 18, 19, 20 and the Inner/Outer Bulls Eye. So the game forces you to hit those marks. To start scoring points you have to actually hit these areas three times or score the double / triple rings. So as you'd imagine the game draws out pretty long. And not to worry... on easy mode, the CPU AI isn't gonna hammer you at the game so you'll get ample opportunity to test different things out.
What works for me mightn't work for someone else and vice versa but I'll give you an example of how I've developed my method: I soon figured out for example that a good way of getting the 18 was aiming the arrow a little right of center, and not lifting the stylus until I reached near the top of the touch screen. Getting a bull is a measured movement down the center. I get 15s by throwing curved from the left hand side of the screen. I've found a sense of method to the game, which I initially thought was kinda gimicky and silly.
As for Bowling -- I actually tilt the DS a little to the right while I play. Similar to the way I tilt paper on a desk when I want to write on it accurately. I can draw straight lines better this way and I never bowl gutter balls. I'm still getting beaten by people who are unaccountably good at the game but I'm still having a lot of fun
