1. Download the installer Application Bundle from the AppStore
  2. Use DiskMaker X to create a bootable USB key.

Make sure to never ever delete the “Recovery HD” partition if you have FileVault2 enabled or are running Yosemite. Apple gives the middle finger to the EFI standard so, instead of installing boot.efi on the EFI System Partition it installs it there (or the primary HFS+ volume).

Time Machine

To remove unused bands in Sparse Bundles:

hdiutil compact -batteryallowed -encryption some.sparsebundle

Fixing Time Machine sparsebundle on NAS