NPA is an intersting phero but not the easiest to use. To get the best out of it, you are going to need to get the hang of accurate mixing in cologne and initially be fairly methodical in finding the dose ranges that work for you.
Do not apply it straight from the bottle, drop by drop! - For starters, the NPA dropper is not accurate and its concentration means you are liable to OD every time.
Also its unscented formula means you are liable to stink quickly and it needs to be well mixed with a scent to diffuse properly.
So that said, the following threads have or link you to a lot of info on NPA and how to use it effectively:
And this thread covers all the basic info on how to use/choose and observe the effects of pheros in general:
