Which Slice to Use

There are two kinds of slices: the normal slice and the reverse slice. The slice puts a clockwise spin on the shuttle (as referenced from the person playing the shot) causing the shot to slow down. The reverse slice puts a counter-clockwise spin on the shuttle causing it to drop more quickly.

For a right-hander, the slice is used when dropping to the left side of the court and the reverse slice towards the right side. This is excellent when paired with the smash - the racquet swings one way and the shuttle flies off at an angle due to the slicing action. As a result we get four combinations:

ATH straight smash -> ATH x-reverse slice
ATH x-smash -> ATH slice
FH straight smash -> x-slice
FH x-smash -> reverse slice

This is ideal when you are well positioned in the backcourt and have the opportunity to take a good aim for your shot. When under pressure, it can be beneficial to perform the opposite slice to curve the shot into the court. This ensures that your shot stays in even while you're a bit more off balance. Here's a video demonstrating an example of this technique: