Coco Chanel once said that a woman should apply perfume in those areas where she would like to be kissed. While this is most likely true (and utterly French), consider the follow guidelines as well.
The Pulse Points
The "pulse points" are locations on the body where the blood vessels are closest to the skin. These spots emanate heat, which can help fragrance to emanate from your skin into the air. (It's the same principle used by essential oil diffusers). Apply your perfume to these points - namely, the inner wrists, the base of the throat, behind ear lobes, in the cleavage, behind knees, and the inner elbows. As you wear your perfume throughout the day, it will react with your body heat and continue to emit scent.
A Word of Caution
Despite the great Chanel's maxim, perfume does not taste good. Keep that in mind when applying yours, and avoid any areas that may be enthusiastically nibbled.
How to Apply Perfume
Applying perfume is the simplest of matters - simply spray, dab, or in the case of a solid perfume compact, swipe. (Do avoid rubbing the wrists together after application, to prevent "crushing" the scent).
Some women enjoy spritzing their perfume into the air and then walking through it. While this does work, it also lets quite a bit of the fragrance go to waste, so it's not the best method if you're on a budget.
Always apply perfume before putting on your clothes and jewelry. Some fragrances will leave permanent stains on fabrics, metals, and pearls. (If you want to risk perfuming your clothing - say, spraying some scent on a scarf - be sure to test it on a hidden area of the fabric first, and spray lightly).
Perfuming the Hair
Misting the hair with fragrance is a great way to leave a gentle scent in your wake, as you move through your day. Those who you choose to get closer to be will also be rewarded with a fuller scent. Be careful only to apply perfume to freshly-washed hair, or the natural oils (and any lingering hair products) will affect the odor. Since perfume contains alcohol and can be drying to your strands, apply sparingly and from a distance. A spray or two from 8 inches away will do.
Making Fragrance Last Longer
There are a few tricks to help your fragrance last longer. For instance, a scent will fade faster when skin is dry. Applying fragrance-free moisturizer to your body is an excellent preparation for applying fragrance, and will help you get more bang for your perfume buck.
You can also help your perfume to go the distance by applying some petroleum jelly to your skin, and then applying your scent on top of that. The perfume droplets will cling to the petroleum jelly - rather than sinking into your pores - which can reduce or eliminate the need to reapply fragrance later in the day.
Layering products from the same line is another effective way to make a fragrance last. You might use the scented body gel, treat skin with the body lotion, and then spray the eau du parfum spray on top. The combination of products will help the scent to maintain fullness and extend throughout the day.