There are any number of NPA threads here if you search eg:
NPA can be applied neat but do remember it is in an alcohol base and from a bottle with a non-accurate dropper. So the chances of controlling dose at your age is next to nil. Still, some guys manage it.
IME, you get by far the best results from mixing it - 1/5, 1/4, 1.5/3.5 npa/cologne in ml are all common dilutions. Dilution with scent also improves diffusion, effective range and limits the potential for NPA to stink like no other phero. Which can also happen if you use it straight.
Age race and other factors do affect matters, however it is nowhere near as simple as saying use more or less drops of this and that - You need to test to find the effective dose for your body chemistry and social situations.
I find I get around six hours effective use per application.