Hi Q,
you can apply many pheromones at once. Of course it’s better to test them one by one first, so you know which does what, and have better idea how to mix them.
I’d suggest you do some reading, here are some wonderful threads worth recommending:
https://pheromonetalk.com/t/read-me-first-helpful-topics-on-how-to-get-around/3106
https://pheromonetalk.com/t/how-do-i-qualify-for-a-25-gift-certificate/19934
Also, take a look into men’s and women’s sections of the forum.
But most of all, tell us more about yourself. What kind of person are you, what’s your personality like? What do you want to achieve with pheromones? Any social difficulties that you hope to overcome?
We can give you better advice if we know what are you looking for 