Sideways block pushing allow Link to push certain blocks in a direction that was not intended by the developers, allowing for some minor skips. Most sideways block pushing utilizes wall clipping.
Below are the various positions Link needs to stand in in order to perform the various sideways block methods. Note that all measurements are relative to the moveable block being pushed to the side.
The above chart suggests that it is best to wall clip into the block by two pixels, as there are three individual positions that allow Link to push the block downwards from the right side.
The above chart suggests that it is best to wall clip into the block by three pixels, as there are two individual positions that allow Link to push the block to the left from below.
The above chart suggests that it is best to wall clip into the block by three pixels, as there are two individual positions that allow Link to push the block to the right from below.