Try to think of everything you smell each day. Most scents come and go without giving you any pause. Every now and then, something catches your nose, and you think about it- there's a memory of it, or a distaste for it, or perhaps it's a scent you adore. Some scents we become so accustomed to, we don't even smell them- the way our homes smell or the scent of our perfumes.
I make an effort to notice every odor I can. Sometimes this is a good thing, other times it's not so great, since the world isn't always a pleasant smelling place. When I walk to my office in San Francisco, I'll catch whiffs of a wide variety of odors within a short amount of time. There's the food form the restaurants I pass, the occasional bits of nature in the form of flowers, trees, or bushes, the more industrial smells from road work or new construction. I smell cigarette smoke way too often, which bothers my lungs, and pot smoke fairly regularly as well- while it doesn't bother my lungs, I think marijuana is rather nasty smelling. Sometimes there's the smoke from a fire, and I hope there's nothing too serious happening at those times.
There's one spot where there's a water fountain, and it has a kind of fake maple sweet smell to it, perhaps like fenugreek. I'll catch someone's perfume or cologne as they walk by- usually thinking to myself that they really ought to be wearing less, especially when I can smell it half a block away. There are odors that I'd prefer not to write about- fortunately those aren't as bad in my area as in others.
The office building is generally one of those places I fell has a neutral odor- I'm used to it. Sometimes I'll get into an empty elevator, and the scent of perfume or cigarettes lingers from the previous occupant. During lunch time there will be food smells, especially if one of the conference rooms has a hosted lunch.
My apartment often has way too many scents to describe- if I'm making something, that will often fill the space. My work space has dozens of essential oils in it, and while the bottles are closed, I feel they contribute to the scent of that room. They definitely make my trash and recycling smell nicer than most people's! Sometimes there will be soup simmering, cookies baking, or candles burning, and those will be the predominant smells. And while I love scented candles, I don't use "air fresheners." Cleaning products might add some odors, but I generally try to find ones that don't smell too strongly.
There's also those smells that are hard to describe, but you know what they are- for me those are the seasons, like when I'm walking, and I suddenly smell "fall" or "summer." They don't always coincide with the actual season, especially now that I live in San Francisco, but when I'm walking around and those scents hit me, they just trigger those seasons in my brain. And while I definitely don't get it in SF, the smell of snow is distinct to me, but I don't think I have words for how it smells to me.