Borgin & Burkes
From the street, a mouthwatering scent entices passers by to enter the shop; reminding them of that favourite dish mother used to make. Once inside, it's obvious this smell originates from the brew bubbling in the cast iron cauldron which dominates the huge stone fireplace taking up half the left wall.
The more shrewd sort of customer will not miss that such a hot welcome is also likely to put off any unexpected visits via floo.
Now that the customer's eyes have adjusted to the lighting, which in the form of gas lamps is bright compared to the all round gloom of Knockturn Alley, they can see that a few paces in front of the door is a set of stairs with a small wooden gate at the bottom such as may be used to prevent a toddler climbing up and tumbling down them.
This gate, however, is clearly meant to prevent anyone accessing the upper levels of the store. Best leave it alone; it's probably cursed.
Walking into the depths of the shop itself, the customer will almost certainly notice the lack of cohesion. Although the shop is neat, nothing is made to measure. All of the furniture is mismatched and second hand. A sapphire ring sits next to a seemingly ordinary river rock. If there is some reason behind this layout, most people cannot see it.
Finally, at the back of the shop there is an antique writing desk. A large, stuffed crow has pride of place in the corner. At least, that's what most people believe until the crow tries to take a bite out of them.