How do collectors establish relationships with auction houses?

The direct way is usually the easiest way. That is: buy and sell art.

Why do auction houses sell sensitive items like Michael Jackson's stolen studio tapes even when their legality is in question? - Quora

Why do people buy celebrity garbage/trash/throwaways at auction? - Quora

How do auction houses work? - Quora

How does an aspiring historic art collector with several thousand dollars saved find pieces to bid on to start their collection? Most online auctions seem to have ended already. - Quora

Why do some of the most savvy collectors in the whiskey industry turn to auctions such as those held by Sotheby's to build out their own shelves? - Quora

How do auction houses work? - Quora

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What is the upcoming auction at Christie's featuring Charlie Watts' personal collection all about? - Quora

What is the upcoming auction at Christie's featuring Charlie Watts' personal collection all about? - Quora