What advice would you give to a newly-minted senior software engineer?

Make a contribution to a Roth IRA (or some other retirement account). The gain isn't taxable, and it compounds in value continuously.

Over the years it will double and double and double again. (And you can also tap that growing nest egg to cover any medical emergencies or for your first purchase of a home.)

Where do “software engineers” get minted?

My best advice comes down to listening and learning, including paying attention to the whole business and not just your tech corner of it. Help and learn from your colleagues — your connections and friends will always have more value than any skills listed on your CV.

Quit while you're ahead!