You can only be a first timer in a city once. There's only once chance to form a first impression of a city and that's quite precious. The first step outside the airport; is it crowded, does it look old, does it smell? The taxi; is it an old car or a shiny vehicle, does the driver speak English? Then the first roundabout on your way, it hints if should you expect a wild traffic in this city.
The street lights, shop signs, width of the roads, posters for art events, all would give some clues, some ideas to form your first opinion. You notice some of them, yet most only register to your unconscious mind.
Then once you settle into your accommodation, you set out to explore the city. This is where it turns out to be a sensory feast. Food specific to that city, shape and height of the sidewalks, what locals wear, accuracy of the road signs, traffic noise or any other noise that is noticeable in that city... Some cities smell like springtime because they have so many trees and parks, some cities smell damp, because of the constant rain and never drying coats and umbrellas, some cities smell like bakeries and some cities have a very macho smell. A city may have one very distinct smell that you associate with it, whereas another one may have several undertones.
Then music... For me, Helsinki is “Pure Morning” by Placebo, Athens is “Tell Me” by Madonna and Muscat is Spin you Around by Puddle of Mudd. I don't know if the city reminds me of the song or vice versa. But once that connection is formed, it is also registered among my first impressions.
You are generally very perceptive with all your senses, at both unconscious and conscious mind to absorb and to understand whatever is going on there. The more foreign the city is, the more you keep your senses open, because you don't have many incidents where you can give in to the comfort of “oh yes, its just like in city x / I have seen that in town y” You are even more alert to absorb in as much as you can...
Here I am in Chiang Mai, for the first time. Whatever it is, Chiang Mai will always be special for me because it is the first city that I've traveled to without a guidebook or a map. I wanted to struggle, get lost, find and feel good all by myself. Since the moment I dumped my luggage into my accommodation and headed out for the city center it's been a sensational and sensory feast for me. The taste of the pineapples that are sold on streets, the colors on the Sunday market, smiles on peoples faces, constant buzzing of the tuk-tuks, … Then the new age cafes, juice bars, trust-fund babies …
I now have my first impression of Chiang Mai, accompanied by the thrill of discovery. Novelty is always exhilarating, especially if it comes from exploring a new place. Maybe that's why I'm homeless, maybe that's why I keep moving around every so often. I constantly seek that feeling and quite possibly get my kick from it. Whatever it is, this is a very valuable experience for me, to see a new city and to be in a new city.
If I stay long enough, I may add considerable amount to my first impression, I may find out contradicting facts, I may even say “what the hell was I thinking when I said that about Chiang Mai?” None would change the senses associated with being a first timer and the power of my first impression. It's very precious.