1. Don’t convert the RMB into your home currency in your mind. This will make you believe the item is really cheap, and in turn cause you to be lax on the bargaining.
2. Because you are a foreigner, shopkeepers will automatically increase the initial price. I have been  able to reduce prices by as much as 75% once I spoke some Chinese and they realized I live in Shanghai.
3. My general rule is to take the initial offer, and then not pay more than one third of it. Now, occasionally there are genuine merchants out there who will offer a fair enough price that you will only need to reduce a little. It is all swings and roundabouts I am afraid. Follow your instinct.
4. Don’t buy from the very pushy sellers!! Remember that another store (if not 50 others) will sell the same goods, so you surely won’t miss out on buying something you want. Maybe this is something very personal for me, but I prefer to hunt out the gentler, more genuine sellers and buy from them to encourage them.
5. Here is my approximate price list but I can only advise on goods I regularly buy:

Gucci sandals - around 50RMB
Billabong t-shirts - around 50 RMB
Hoodies - No more than 120 RMB
Diesel jumpers/cardigans - around 130 RMB
Bras - 60 RMB
Panties - 10 RMB for cotton, more for silk
Silk dresses - don’t do it!! Email me for info on tailors who will make it cheaper and to fit you perfectly.
Table settings with chopsticks - 15 RMB
Chinese sequined shoes - 120 RMB

See another Synotrip article on bartering