Do expect Copenhagen to be just like the Lego that was spawned down the road in Bilund 80 years ago: small but perfectly formed. The same can be said for the supermarkets, bicycle lanes and the Little Mermaid.
Do check homeexchange.com for Copenhageners eager to swap your home for their flat, which may well be furnished by a Scandi design master like Arne Jacobsen or Finn Juhl. If it has to be a hotel, make it Jacobsen’s retro pearl, SAS Royal Hotel.
Don't cross on a red light. Danes will stand and wait for the light to change on a deserted road, at two in the morning, when it’s pouring with rain.
Do download the free interactive app "1001 stories of Denmark", for a portable guide to the historical sites and hidden cultural gems (at the App Store and on Android).
Don't pass up a schnapps for lunch along with your smørrebrød — an open-faced rye-bread sandwich topped with herring, chilled potato, sliced egg, or baby shrimp and dill.
Don't be offended if Copenhageners bump into you, don’t introduce you, don’t serve you immediately, or don’t hold the door for you. Although well-travelled, many Danes are paid too well to go out of their way for you (google: the welfare state).
Do rent a bike. Everyone aged five to 85 rides one, and with good reason. It’s the easiest and most scenic way to get around. Remember to mind the traffic signals and to lock it up: in Copenhagen a bike gets stolen roughly once a minute.
Do go to the Vesterbro or West End, a palimpsest of Copenhagen’s past, present and future. Cool and cultural, Kødbyen (the Meat Packing District) is bursting with independent galleries and stylish restaurants. At Fiskebaren, taste the Nordic cuisine made famous by René Redzepi of Noma, then dance and drink through the light summer nights at Jolene and Karrierebar.
Don't waste time (and elbows) on Strøget, the overcrowded pedestrianised street. Instead, stroll down the parallel, cobblestone Strædet, or head towards the King’s Garden for local shopping, café life and people-watching.
Don't visit during November when the weather is at its most dreary and grey, unless you’re channelling your inner Sarah Lund. If you’re craving one of her staple Faroese sweaters by Gudrun & Gudrun, you can always get it online.
Do enjoy the water. Danes are still Vikings at heart and embrace the chilly sea: take a dip in the harbour baths at Islands Brygge, or hop on the touristy but still lovely canal boat tour, which will float by the Black Diamond (the Royal Library), Opera House, and Trekroner, the old sea fort which protected Copenhagen at the time when Denmark ruled the waves.
Don't ask for a "Danish" when you go to the bakery. But...
Do eat a Danish, or Wienerbrød (Vienna Bread), at Lagkagehuset, or any authentic Danish bakery – spot them by the symbol of the golden pretzel above the door.