1. Don't be embarrassed If you don't ask, you won't get. Everyone is at it, so don't be shy! In many cases, a sales assistant will expect it, and a margin may be built into the price.
2. Know where getting a discount is more likely Haggle for everything, especially electrical goods, furniture, cars and hotel rooms. If renewing an insurance policy, make sure to quote a cheaper premium you've been offered.
3. Always be polite Being polite and courteous is the way to go. The salesperson is not the enemy.
4. Be realistic Don't be unreasonable and suggest a massive discount that isn't feasible. Remember this is a business deal and the retailer has to make a living too.
5. Use positive language It's all in how you say it. Use positive language and not weak statements like "Could you knock-off something?". You're not after a "no" answer but a friendly dialogue. You could ask "How much are you going to knock off the price for me?"