I think you'll find the answer you're looking for in concern to "notes" here
http://en.wikipedia.org/wiki/Base_note
If that's not clear enough for you pm me and I will try to give a better plain English explanation. I actually make my own colognes and aftershaves, although I do buy commercial scents as well because I just can't achieve certain scents I like sometimes. With that said, I feel I can probably field most questions you might have about cologne.
What cologne you should wear can depend on many factors including, but not limited to: the occasion, your age, your significant other's preferences, what time of year it is, and believe it or not even the selection of colors represented in your clothes. Scents are in many ways just like colors, some are bright and energizing, others are dark and somber. If you wish to achieve a certain "aura" with your style and scent it is usually more effective to make sure your scent matches your appearance once you better understand the intricateness of the world of scent.
Just remember anyone can spritz on a store bought scent, and being a commercial scent, you have to accept there are many other people out there who will smell just like you. The trick is to "make it your own" in the eyes of those who meet and, in turn, smell you. You don't want someone to smell your cologne or something similar elsewhere and say "That smell reminds me of that cologne (your name here) wears"....you want them so say "That smell reminds me of (your name here)" ...It's a small but distinct difference(if you google it, there are several guides on how to "make a scent your own"). The sense of smell above all other senses is most closely connected to memories. A perfect example is how many members say they keep products such as william's shave soap and old spice aftershave around because it reminds them of their fathers...a scent can stay with you and awaken old memories many many years later.
As far as the proper way to apply a cologne, first you need to decide if you want a spray/vaporized scent or a open top "splash" scent. If it is a sprayed scent the proper way to apply is to actually give one to two quick strong sprays at head level in the air in the space about a foot in front of you, as the mist settles walk forward into the "cloud" and let it settle on your torso region.
A splash scent is best applied on the underside of the wrists, then rub your wrists together briefly then dab any remaining cologne on your neck just below the ear.
Well I think I've covered everything I could, but if you have more questions, feel free to pm me.