Creating a OS backup image for an easy restore on a new system
The easiest way to copy your old setup (including your data) onto your new machine is to use Migration Assistant on the new model. This requires both computers to be connected "somehow" (with this "somehow" being as fast as possible, so a LAN is usually better than WLAN for instance). 

If you don't have access to both machines simultaneously, I would use an external drive, use Disk Utility (or CCC or SuperDuper!) to create a full backup of the old computer and then use this backup as the data source for Migration Assistant. Creating a full image usually is faster than using Time Machine, you can then use the drive as a Time Machine destination after the migration.