Every guide to flea-market shopping gives you the same commandments. I have broken all of them, repeatedly, and my house is better for it.
Yes, haggle — but when a fair price meets a good dealer, pay it and make a friend worth more than the discount. Yes, travel light — but the caned settee I could not carry is the best thing in my sitting room, and the taxi cost less than lunch.
The one rule I keep
Walk the whole market once before buying anything. Desire needs a lap of the aisles to sort itself out from habit.