Let's start with the most common myth: That perfume smells best on pulse points, specifically the wrists and behind the ears. Though it's a nice spot to bring up to your nose gingerly, you might be doing yourself a disservice. According to renowed perfumer Jean Claude Ellena (current in-house perfumer for Hermès) the Ph of the skin on the inside of the wrists can be a bit acidic/sour, thus subtly swifting the aroma of your fragrance. This is especially crucial with fragrant compositions which present tart or floral notes. Additionally, wrists are the places we often wear a wristwatch, bracelets or other jewelry and use to rest our hand on a mouse pad/handrest (here's a very pretty one!). These are materials which can also influence the scent of your perfume. A metallic watch or bracelet interacts subtle, while a leather band lends its own inherent aroma to the mix (sometimes in a good way and sometimes in a bad way). Not to mention that in the case of a mouse pad the transfering of different perfumes ends up in a haphazard mix-up rather than a deliberate olfactory collage.
A better area to use, if you want to be able to lift up your fragranced body part to your nose at any given time to enjoy, is the upper hand or upper forearm. Not only are these areas with a more consistent Ph acidity with the rest of your body, giving you a truer picture, the existence of slight fuzz (or actual hair for the gents) aids the projection of the fragrance to those around, prolongs its lasting power and aids its wake (what the French call "sillage").
Behind the ear is a rather bad place for perfume, too even if very evocative, immortalised in hunderds of advertisements and films due to its erotic significance of ear lobe kissing & suckling, because at the back of the ears there are glands which produce an oily-smelling substance which distorts your posh perfume. You can judge just how much your own glands produce by rubbing a wet towel behind that spot and sniffing (or giving a long sniff at the sidebands of your spectacles/sunglasses). Heavy consumers of dairy products will notice a curdled milk, butyric note that is rather displeasant (and which prompts the Japanese to consider Westerners as "dirty"-smelling). Those who eat a lot of spice will have a production of sulphurous byproducts which can make their fragrance smell rotten, heavy or sour.
The best practice is to forsake behind the ears application for the front of the neck (assuming you don't wear neck jewelry, especially pearls which get tarnished by perfumes). This also aids the trailing of your fragrance during social hallos, as the scent rises uniformly during being given kisses to the cheeks.
Spraying in a cloud in front of you and then walking through the scent mist to get just the right amount is a technique which began by the launch of Aromatics Elixir by Clinique in 1971. This method was especially divised to cater for the bombastic blast of this superperfume and was then transfered through all of the Lauder Group companies.
It is rather wasteful so best used for anything that has a projection and trail as big as a house (most Estée Lauder scents indeed), so it's perfect for Angel and the like if you're wary of offending but still want to wear such a powerhouse. (In the case of Angel, even waving a Q-tip soaked in it in front of you is enough to transfer enough scent for you to smell of it!). Use it if you're adamant that spraying in profusion is the last resort of luxurious abandon in a rationed age.
Another common myth says you're not supposed to spray on your clothes because that way perfume doesn't get the chance to interact with your skin. Though it is a wonderful, romantic notion, giving every woman the idea that her fragrance is hers alone, because magically the scent is different in accordance with one's skin, this is a marketing technique that was specifically conceived for Chanel No.5. To make the iconic Chanel perfume regain a bit of its individual cachet after the mass popularisation of it, following its exhibition in the army shelves market during the 1950s, some new approach was needed. According to author Tilar Mazzeo, in her book about the venerable classic and its history, the Wertheimer brothers devised this plan to make No.5 not lose its sense of being a precious commodity even though it had become a bit too accessible. (This was a concern after the infamous days of American GIs photographed standing in a long line to claim a bottle of the classic perfume at the Parisian boutique during Nazi-occupied France). The plan worked: The marketing line was added even into commercials well into the 1970s and Chanel never became Coty or Dana. Most contemporary fragrances -excluding all-naturals artisanal perfumes and a few with a particularly high ratio of natural ingredients in them- small exactly the same on most skins. Think about it; this is why we're so quick to recognise their trail on a stranger on the street or across the cinema!
Therefore, unless we're talking vividly coloured juice (such as Serge Lutens Sarassins which is deep purple and stains like ink would), you're quite safe with spraying your clothes (apart from silks). If in doubt, a small secret patch test on an inside corner will convince you. Perfume is retained best on cloth, especially natural fibers (linen, cotton, wool) and rich aroma materials such as vanilla, amber, resins and balsams of the oriental & floriental family (hence the concept of "cashmere wrap fragrances" or "scents on a wool scarf").
One especially neat idea is spraying the flanks of your body, extra handy when wearing a jacket, as the natural movement of your arms brushing off when walking releases and re-releases fragrant molecules as you go through your day. Yet another nice spot is under the jacket lapels, or spraying a handerchief and tucking it in your breast pocket. Spraying your clothes also presents the advantage of extending the perfume progression's arc, making the notes appear in slow motion; especially nice with fragrances with complex bouquets and full-bodied character in which you want to savour every phase.
Skin does play a role into how scent "holds", but not how you think it does! In the movie Chéri (based on Colette's novel by the same name) the older courtesan, played by Cathy Bates, says to her -poignantly coming to terms with aging- peer Michelle Pfeiffer (as Lea) "you retain perfume so much better now that the skin isn't as smooth as it used to be". This very characteristic observation of La Belle Epoque is also confirmed by top perfumers working today, who add that the same applies to people with big pores; which -I infer- might explain just why oily skin (which often is more "porous"/bigger-pored by nature) retains scent better and longer. It might also explain why some obese people are considered "smelly" by some in the general population (it's not that they don't wash enough, but sweat might get trapped in skin folds).
The fascinating part is it all turns out to be a matter of simple physics, rather than of chemistry!
Hair is a particularly good spot for perfume. Sales assistants might say anything to discourage you from it (from implying your hair might catch fire if a stranger holding a lit cigarette stands close enough, to saying it will completely dry out your hair and wreck it). They're in the business to sell as much products as possible and there are now hundreds of hair mists and hair enhancing scented sprays to buy (incidentally, notably good are those in the Thierry Mugler, Narciso Rodriguez and Chanel ranges, quite true to the actual perfumes). Buy them if it makes you feel all pampered up and you're a completist, but if not, you're just as well with spraying your hair brush or doing a quick spritz/dab on the nape, letting hair pick up the scent and release it with every move of your head. Frederic Malle agrees:
"For a special occasion, apply perfume on the back of your neck. The heat rising up your body and the movement of your hair will diffuse the scent. Also, the oil in your hair is a fabulous fragrance keeper, so you could spray some in your hair too. Just don't do it every day because the alcohol will dry out your hair." [source]
Pop perfume lore handed down by sales assistants tells not to rub your wrists together when you apply perfume "because you'll crush its molecules". Nothing could be further from the truth! Molecules are not that sensitive to physics, otherwise the time-space continuum would have been shattered long ago. The most you're going to do is annihilate the top notes through friction (which generates heat, which in turn will aid the rapid evaporation of the most volatile ingredients in the perfume, the so called "top notes"). You're essentially losing the introduction to your personal fragrance. Given that many modern fragrances are specifically conceived to display a particularly attractive overture so as to catch the attention of potential consumers, it's a shame missing it! On the other hand, this is a quick & practical way to judge the "heart notes" or "core" of a fragrance (the middle stage) you're eager to get into, when pressed for time. It will give you an immediate idea of what it's about beyond the usual 30-minute window frame given for the dissipation of the top notes. Proceed accordingly.
When not wanting to offend with your fragrance in an office setting or in close proximity with other people or in hot weather, you might want to consider other tricks to tone down your perfume's potency. One simple trick is to spray your calves (not the back side of the knees when it's really hot, as these naturally sweat a lot when we bend them to sit down) and let the perfume rise slowly. Since noses are stuck in the place they are and you're typically not dealing with midgets, most people will get a small amount of rising perfume and not a full blast coming off the neck and decolletage. Another, especially welcome tip for romantic rendez-vous is spraying your belly-button (make sure it's free of lint too!) or under the breasts (or the equivalent spot for men): The belly is warm, the scent rises uniformly and you're guaranteed a restrained sillage that gets more intimate & intriguing as clothes get off....
Last but not least, there is "the cotton ball technique" of applying perfume. This does not consist of dragging a perfume-soaked piece of cotton wool on your body to spread the scent. You would be wasting precious juice that way, as cotton wool is so very absorbent. Instead you're supposed to lightly soak the cotton ball with fragrance and then tuck it inside your bra. This provides a subtle scent that you yourself can perceive at all times (a little tilting of the head can confirm it) while it doesn't suffocate everyone around.
Back in the old days they had a more romantic technique; dabbing from a dab-on extrait de parfum bottle using a silk handerchief which was then used to simply aromatize the insides of a feminine purse. Isn't it totally sublime? That way you're not contaminating the perfume with skin debris from your fingers or through transfering with the perfume dauber/stopper and you have a scented memento you can toss at any aspiring beau....
Related reading on Perfume Shrine: Perfume Myth Busting, How French Women Apply Perfume.