Get to the auction at least twenty or thirty lots prior to your sale: that way you will understand how the auctioneer is working, how he takes bids, his increments, and the pace at which he is moving. You can get used to the whole atmosphere.
Don't worry about gestures being mistaken for bids: auctioneers know if someone is bidding. If it looks like you are waving to your friend or scratching your eyebrow, they would not take that as a bid, or would certainly make sure by asking you.
The bidding will usually start at about two thirds of the lowest price listed in the catalogue, with the increments normally being 10 per cent of whatever the price is.
Just raise your hand to make a bid. Sometimes you can tell if people bidding against you are going to pull out. Often they start conferring with another person. Or they will say, "No," and then try one last stab, raising their hand reluctantly. That's a sign you're about to get your piece.
Don't bid on pieces that you had not thought about or seen prior to the sale, and try not to get hysterical. Concentrate on the piece and on the price that you have already decided in your mind, and stop if you can no longer afford it.
Remember: as soon as the hammer comes down, that's it. You've bought the piece and you've got to pay for it.
Benjamin Brown is director of the Contemporary Art Department at Sotheby's