Give them a trial run. Like anything new, it's good to test pheromones out to see how they work for you. Wear some while you have your Sunday morning latte and read the paper at the coffee shop. Spritz it on when making a run to the grocery store. (Be careful when you take your dog for a walk. Other dogs you pass might pick up on the scent and become very interested in you.) These are low-key situations where you can gauge if more men seem to look at you or try to get you to talk to them.
Pick an appropriate setting when you use pheromones. Friday nights at happy hour, club hopping, a fifth date, a reunion with your old high school crush---those are the times the chemicals are made for. Some people like to use them in business to increase their confidence or to improve their relationships, since the salesman you like the most is the one you're going to buy from. But baby showers, ladies' teas, family dinners, funerals---there's little point to wearing any in these situations.
Choose wisely whom you use them around, even if the setting seems ideal. The hormones are supposed to make all kinds of men responsive---and that could include your boyfriend's roommate, your boss or your best friend's husband. Men are of course responsible for their own actions, but there's no sense using pheromones around someone you aren't interested in. Another aspect of this scenario is you don't want a guy you've been fending off---like a pushy neighbor who lives in the apartment next door---to become even more interested in you. If you use them to try to attract a co-worker, you could end up attracting the gangly intern instead of the junior buyer.
Apply the pheromones to a pulse point on your skin by dabbing (concentrate) or spritizing (spray) them on. These would be on your wrists, behind the ears, around your neck and the backs of your knees. You only need to apply to one location (the wrists or the knees, but not both places).
Put your body language to work. Catch a man's eye that interests you for a few seconds, then look away. Casually do this a few times. Sit with your feet pointed in his direction, with your arms casually at your sides. You'll probably catch yourself playing with your hair. You want to look like you would invite having a conversation with him, which will increase his confidence . . . and his chances of approaching you.
Back up the pheromones by looking your best. Invest time in learning how to chat with strangers and being a good flirt (see Resources). Remember that the pheromones are only an aid. It doesn't do any good to get the attention of every man in the room if you can't carry on a conversation or don't put any effort into your appearance.