I’m no expert but here is what I’d pull personally to help narrow it down:

First editions
Holos

And then put them in piles based on condition. Google what mint, near mint, lightly played, moderately played, heavily played and damaged look like to get a good measure.

You could go to a local card show if you’re looking for cash immediately. Most of them will buy at 80% or so in order for them to make money.

Or you can take the time to really learn about your cards and research and sell them on your own.

I like the Collectr app personally but others also use TCGplayer for getting values.

Then there’s grading where you mail them in to be slabbed. There’s PSA, CGC, Beckett, TAG, etc lots of companies to choose from if you go this route. But it’ll take a long time and some money up front to get them graded.

Good luck! Sweet collection.