Hi there, welcome to PheroTalk! 
What’s your personality like? Also how does a typical interaction with girls go, and in what settings(club, work, etc)? Are you looking for an LTR or just sex? There can be many reasons why girls might turn you down so a little more background information is needed.
The biggest thing is to remember that women are unique, individual human beings, and so are YOU. You want to come across as confident, fun and friendly, not seedy or desperate or scary.
Pheromones can’t turn things around 360 degrees. They will only enhance the qualities you already have. The more ‘YOU’ that you can supply, the better results the pheromones will bring. 
Focus on yourself first - hygiene, style, communication, posture, behaviour, confidence, language, manners and body language are some points to think about. Make sure you’re not hiding your strengths (for example: sense of humour, great smile, good dancer, manners) away, and please don’t bother with so-called ‘pick-up’ ‘game’ tricks - I assure you that is not what you need right now!
Product wise, it is recommended that you learn how to use individual products before you wear combinations. I would recommend Instant Shine as the phero to begin with. It is a fun, feel-good pheromone that exudes confidence - which is very attractive from a female point of view. 
Good luck, and don’t hesitate to ask for more guidance from the knowledgable members of the forum!
See you around,