Start from Muggle London.
The magic starts for Harry when Hagrid takes him to the Leaky Cauldron, hidden in a back alley in Muggle London, so you should start on the Muggle streets, too (ease yourself into the Wizarding World)!
Either way, you'll check out locations like Stoney Street, where the entrance to the Leaky Cauldron was filmed, and Leadenhall Market, which inspired Diagon Alley.
Don't forget to stop by the zoo and check no one's abusing the snakes.
Harry does his first bit of magic (and speaks Parseltongue) at the Reptile House in the zoo. Slytherin fans will appreciate that it's also a bit like a mini Chamber of Secrets.
Then it's time to stock up on school supplies.
First-years will need a wand, a cauldron, and a Wizard's Chess set!
And it's the best place to stock up on Howlers so you can make yourself heard when people make you mad during term time.
Steer clear (or don't) of Knockturn Alley.
Goodwin's Court near Covent Garden inspired J.K. Rowling when she wrote about Diagon Alley's evil twin street, Knockturn Alley, and according to Muggle Tours, the film crew tried to shoot in the narrow passageway, but couldn't fit their equipment through!
Make your way to King's Cross Station.
The moment you've been waiting for! Pack your train ticket and head of to Platform 9¾ at London's King's Cross Station, but be careful not to mistake the grand facade of St Pancras International Station next door for King's Cross. The Harry Potter filming crew used St Pancras as a stand-in for King's Cross several times, since the real thing was under construction, and since St Pancras is prettier, to be honest.
You can pick up some last-minute school supplies.
The platform can be a bit busy these days, with more and more Muggle-born wizards heading to Hogwarts, so be prepared to queue if you want to buy some house patches, Quidditch gear, and whatever else will fit in your trunk.
And load up on sweets and treats fr for the trip.
Though if you're looking for specialty items like Fizzing Whizzbees and Sugar Quills, you'll have to make a trip into Hogsmeade or Diagon Alley.
You can even grab a wand if you left yours behind like a total Muggle.
You can buy a wand modelled after anyone in the Order of the Phoenix or Dumbledore's Army, and even some Death Eaters if that's your style. The shop is often sold out of 11-inch holly wands with a phoenix tail feather though, so consider a nice elder wand instead.
Drop your new goodies off at your dormitory.
Then head to the Great Hall for some Butterbeer and the Start-of-Term Feast!
For all the gaps that Muggle London leaves in your magical experience, the "Making of Harry Potter" tour at Warner Brothers Studios on the outskirts of the city is there to fill them in.
Sneak through a secret passage into Hogsmeade.
You can see all of the film's artwork (and buy so much Wizarding candy you'll guarantee yourself a visit to Hermione's dentist parents).
Floo to the Burrow to try the newest Weasley's Wizard Products.
And you'll see most of the places in the Wizarding World that are hard to reach from London.