You already know fragrances are powerful. They're complicated, too. Fragrances are actually broken up into five broad categories: floral, oriental, woody, fougere (fernlike) and fresh. To make it even more challenging, many scents are also blended from a number of ingredients within those five categories. The idea is to create a composite fragrance with three notes that evolve and change as the ingredients are exposed to light, air and the heat from your skin. A fragrance's top note is immediately apparent when the scent is applied. It's the smell you probably most associate with the fragrance. The middle notes start to emerge as the top note fades. It's somewhat deeper. The lingering base note asserts itself as the middle note dissipates after a half-hour or so. It's richer but probably doesn't have the fresh appeal you loved about the scent when you first put it on.
This all means the scent you applied at home this morning with, say, your hand lotion, will start to smell very different within less than an hour. Yikes. A flowery, fresh scent could take on a musky smell or a woodsy scent could begin smelling more masculine than you'd like.
That's where scent layering comes in. It's actually the process of coordinating the fragrances you wear so they'll be compatible and stay fresh and pleasant smelling all day. Remember, you may actually be wearing fragrances from your laundry detergent, your shampoo, hair conditioner, bar soap, hand soap, deodorant, moisturizer, cosmetics and cologne (and possibly other fragrances, too) on any given day.
There are a couple of ways you can deal with this abundance of aroma: You can just douse yourself with cologne to cover up every other fragrance and be done with it. This might seem like a quick, easy solution, but it doesn't work very well. Your cologne will smell overpowering for a while, but eventually the underlying fragrances will assert themselves. (This will likely be long after your co-workers have decided to open all the windows and hang out in the conference room.)
The better solution is to choose your fragrances so they'll all work in concert. The easiest way to do this is to buy complementary products produced by the same manufacturer. Every few hours, reapply your cologne or perfume to renew its top note freshness and you're set. The idea here is that different products like your shampoo and scented talc will be absorbed into your skin at different rates and change fragrance notes at different times, a bit like the way individual instruments in an orchestra create depth and resonance. They're designed to work together, so there are likely to be few if any unhappy olfactory surprises.
If you can't coordinate all the fragrance elements you're using -- and it can be a challenge -- try choosing fragrance-free personal care products whenever possible. They won't interfere with your expensive colognes and lotions. There are also lots of them on the market, and many of them have the advantage of being hypoallergenic.
Another option is to choose a simple, single ingredient (one note) fragrance you know is pretty universal like lavender, sandalwood or jasmine and mix it with your main fragrance. If it's compatible, you can use it with your designer blended fragrance cologne or perfume without worry. Many major personal care products are available in one scent varieties, so coordinating the fragrances you're using should be pretty straightforward. The process may take some experimentation, but your nose knows. When you have a winner, your combined fragrance will smell as good after three hours as it did when you first put it on -- a little different, but still pleasant and satisfying.