The souk quarter is entirely pedestrian and gets very narrow in places. Donkeys carrying deliveries have right of way — step to the side when you hear the bells. The lanes do not follow a grid, and your phone GPS will lag behind the twists, so download an offline map of the medina before you arrive.
Haggling is expected in the souks. A reasonable starting position is to offer 40–50 percent of the opening price and meet somewhere in the middle. Do not start negotiating on something you do not intend to buy — that creates genuine awkwardness. If a vendor says "last price" and walks away, they often mean it; if they follow you, there is still room to move.
Unofficial "guides" who approach you near Jemaa el-Fna offering to show you the souks for free are almost always on commission from specific shops. A genuine private guide booked through a reputable tour operator costs more upfront but saves you far more in overpriced merchandise.