Persons of magical power present themselves as ordinary as part of the setting.
Linkara: This was not what I was expecting.
Steven the Wizard: What the hell do you want? It's 2012. There aren't a load of people living in gloomy castles, standing over crystal balls and crap like that.In a fantasy setting, the Robe and Wizard Hat is a great outfit for a great sorcerer. In Urban Fantasy or Magic Realism (or any other post-medieval setting), however, it can look silly and clash with the more grounded aspects of the the setting. By giving the magic users clothes that wouldn't stick out like a sore thumb in the middle of a crowded street, the realistic look of the world is preserved. And don't expect them to dwell in a mysterious lair, either. This can also give an air of mystery to the wizards, as it hides the strength of their powers and also implies that anyone could be a wizard. The image of a magician in top hat and tails is the basis of this trope. Prior to the Victorian Era, most stage magicians dressed like Merlin. Then, a few entertainers decided magic would look more amazing if done by someone in (at the time) contemporary evening dress. Penn and Teller update the tradition by dressing in ordinary suits and ties. Compare Not Wearing Tights. Please only note examples where this is brought up or becomes relevant to the story. Otherwise, it's just an incidental detail.
...a pair of men who were having a heated argument. One of them was a very old wizard who was wearing a long flowery nightgown. The other was clearly a Ministry wizard; he was holding out a pair of pin-striped trousers and almost crying with exasperation. "Just put them on, Archie, there's a good chap. You can't walk around like that, the Muggle at the gate's already getting suspicious--" "I bought this in a Muggle shop," said the old wizard stubbornly. "Muggles wear them." "Muggle women wear them, Archie, not the men, they wear these," said the ministry wizard, and he brandished the pinstriped trousers. "I'm not putting them on," said old Archie in indignation. "I like a healthy breeze 'round my privates, thanks."
When people see my red curly hair, fair skin and long goatee, they suspect I play soccer and drink lots of Guinness. If I'm going sleeveless and they see the tattoos all up and down my right arm, they assume I'm in a rock band and smoke lots of weed. It never enters their mind for a moment that I could be an ancient Druid--which is exactly why I like this look. If I grew a white beard and got myself a pointy hat, oozed dignity and sagacity and glowed with beatitude, people might get the wrong--or right--idea.