Having bought 2 in my lifetime so far my approach has always been to say bugger all to the agent. I owe them nothing. If I have questions I ask, if they ask me questions I give them the most limited information possible, obviously being polite. I always kept my cards close to my chest until it was time to lift the auction paddle.
Say very little; it’s none of their business. Dress how you normally would.
Plain grey ball cap every time I step outdoors in anything less than smart casual. Slip slop slap and slide, kids.