Article in English: Do some preliminary "homework" by searching the Internet or visiting other stores to find the lowest prices for the item you want.  Printing out a counteroffer or writing down the website to show the seller during negotiation demonstrates that you've done your research and are willing to go elsewhere. Make sure you're looking at comparable products. Just because you found a used model for half the price doesn't mean you can get a new one for that amount. If you're considering a house, ask a real estate agent to provide you with a list of comparable listings and sales. Also find out how long the house has been on the market — the longer it has, the more willing the owners will be to sell it at a discount. Familiarize yourself with the product's features and how they compare to similar products. The more knowledgeable you are, the better you'll be able to judge the terms of the deal. When negotiating over expensive items, looking your best will garner more respect from the other party. This is especially true if you're negotiating over a house.#Be discreet in your negotiations. If you're purchasing a television or car in a public location, the seller won't want nearby customers to discover they can get a cheaper deal. Keep the volume down and the conversation private to get the best deals. Your earlier research should give you a good idea of how much "wiggle room" you have. Be careful not to undershoot and offend the seller. When shopping for houses, a polite offer is usually 5 to 10% below the listed price. If they don't agree to your offer, you'll need to give them a reason to change their mind. It's difficult to haggle over very expensive items simply by naming prices back and forth.  Point out your loyal customer history if you have one, or offer an additional benefit. If you're buying a car, for instance, offer to have the car serviced at their garage if they sell it to you. If you're selling a home, agree to pay for a repair. Discuss any flaws in the product, however minor. A small dent or a feature that...

Summary in Indonesian:
Carilah informasi sebanyak-banyaknya. Kenakan pakaian rapi. Buatlah tawaran awal yang rendah, tetapi masih masuk akal. Beri alasan bahwa harga tersebut layak diturunkan. Tanyakan jika ada kupon diskon, harga promo, atau potongan harga untuk pembayaran tunai. Teruslah berunding hingga Anda mencapai harga yang disepakati. Periksalah setiap transaksi dengan saksama.