Proper Aiming is fixing the crosshair aiming with Bows or Spells. To see examples of how it works in vanilla and then with Proper Aiming see the page file description.

It mainly works with custom cameras that has the character on one side.

[Install]
Extract in your Data folder
Enable Proper Aiming.esp in SkyrimLauncher.exe

[Uninstall]
Disable Proper Aiming.esp in SkyrimLauncher.exe
Delete Proper Aiming.esp from your Data folder.