Recently, I've discovered a hobby: fragrance. However, I still have a difficult time figuring out how much I should apply. There is currently another scent topic floating around so I know at least a few of you wear it occasionally (and yes, I know that different colognes have different strengths, but I'm just trying to get a ballpark idea). Any advice gentlemen?
The cologne I wear has one of those little spritzer heads, only sprays a little bit with each one. I usually spray one on the neck, one on the chest, and one on one of my wrists, then rub them together lightly. It's just enough so that people standing within about a foot of me can smell it, and (being in high school) girls usually want to get closer to smell it.
Others have already said it but I think less is more. Also, in many situations, none is appropriate. Many are allergic. If you are in an environment where others can't escape you (and fragrance is volatile, it takes very little to affect some people even when they are sitting far away) like a classroom or an office, wear none. But going out on the town or something. Go for it.
I sing in a church choir, and never wear cologne for practices or performances.
It can really mess some people up otherwise.
I found this quite helpful as it caters to different situations and preferences.
I'd go out on a limb and say to never wear any at work. One man's Garden of Earthly Delights is another man's Garbage Barge on a Hot Summer Day. You really lose credibility if you're making people's eyes tear when they're around you.
If you smoke, NEVER wear cologne. Your sense of smell is shot, so what seems like a little bit to you will be enough to cross other people's eyes.
If you're going out to eat, avoid the cologne - it can interfere with your companions' enjoyment of her/their food.
If you're going on a date with someone you've been dating for a while, use discretion - make sure it's a smell she likes on you, and keep it subtle. Otherwise, you'll be known as "Mr. Never-Gets-Lucky".
As others have said, with cologne, less is more. None is often the most.
Have you considered something with less longevity, like aftershave?
I use a little dab behind and eyes and on my neck and sometimes a rub on my wrists. Only use around three-four drops at maximum.
The cologne I have been using for the last couple years is Armani Code. It's about $60 for a bottle that should last you about a year if you use it sparingly once a day or so. A great subtle smell - almost like a talc smell. I do one spray in front of my upper chest/neck area and walk into the mist. If I'm feeling randy, I'll add a small spritz to my wrists and rub them together.
Fragrance is an odour, not a hobby.
As for your question, the answer is "as little a humanly possible".