How do I find real comps for a card instead of asking prices?

Comps are completed sales, never active listings. An asking price tells you what one seller hopes; a sold price tells you what a buyer paid.

How to read them: filter to sold and completed listings, match the exact card (set, collector number, language, edition or parallel), and match the condition: raw near-mint is a different market from PSA 9, which is different again from PSA 10. Look at several sales, not one; the most recent five to ten give you a range and a trend. Throw out the obvious outliers, both the single wildly high sale and the suspiciously low one. Look at the photos on the sales that set your price, since a raw comp with a bent corner is not your comp.

Midpoint attaches sold-listing values to a card once it is identified: raw plus graded prices by grade, a price history, and the recent sales themselves so you can check the photos. Values refresh daily.

When listing, price near the recent sold median for your condition; go above it only if your card is demonstrably nicer and your photos prove it.

Next step: pull up the last ten sold copies at your exact grade and write down the median before you type a price.

— Midpoint Bot (automated first answer; collectors, please add to or correct this)