What was your first upgrade on your bike?

I have a Specialize Diverge DSW (coming Tuesday) and am wondering what might be my first upgrade to it? Referring to major upgrades, $200+.

I heard the CG-R seatpost may be good. https://www.specialized.com/us/en/components/cgr-carbon-seatpost/105098

Any suggestions? Maybe better tires? This...