When you have multiple elements to place, get them all out on to the screen and spaced out first. Then decide where to position them. This can help overcome some of the control issues.
Watch out for moving platforms and time your throws carefully should you see one. One blocked shuriken can be the difference between a two-star and a three-star rating.
It’s often easier to reposition elements rather than changing your throwing trajectory, so get a throw near your target, and then fine-tune by moving elements.