Hi jonny - Welcome to Pherotalk. 
Well, I hope you will find this the best place - Products are excellent and AD does not go in for the gross oversell and dubious claims that abound with other phero sellers.
37 is not by any means old and you are certainly not too old to be pursuing relationships with women in their mid twenties. Plenty do look for a more secure, stable and focused “older” guy. I’m in my late 40s and frequently get assumed to be ten years younger but still get good interest from women from their mid 20s-up, although mid 30s and over is my preferred age range.
To start off with, you should read these threads carefully - All the basics on choosing and using pheros effectively are well covered:
As for what to start with!
I’d suggest you consider Ammo, Instant Shine, IO or IG and IG. Why:
Ammo is a balanced, all round sexy/social/attractive mix containing none but is usable in a wide range of social situations. You will need to test to find your effective dose with this - see “Sweet Spot”
IS - A great happy/feelgood and socially confident formula that complements Ammo superbly and steers it into great fun/happy territory. Also probably the most all-round phero that AD sell. Great on its own or in combo in so many situations.
IO/IH - Different proportions of alpha and beta androstenols. IO promotes flowing conversation and is a great icebreaker, whilst IH promotes deeper and more bonding talk - perfect for getting to know someone better.
IG - Androsterone, makes for a mature, suave/smart/social impression that impresses. However, IG is not nearly as heavy on the status/maturity as A314, which can put-off younger women as a bit too serious/LTR-minded/unapprochable, although otherwise it is a superb phero for work/professional status and general standing.
As you are in your 30s, it might be worth considering the 2x or “heavy” version of Ammo because we tend to produce less none as we age. However, younger women also tend to be responsive to lower levels of none compared to older and can be repelled by higher/very overt doses (but you do get exceptions!) So finding your effective dose in particular social situations is important and maybe best to do this with 1x frst. Then if the doses work out, 2x can be a good economy measure.
Along with the aforementioned A314, TUTH is worth considering as a second line more overt product - Mainly designed for use in an established sexual relationship, it can still be very useful in clubs, parties and other very sexually charged situations, esp when softened by the likes of IO or IS. Don’t wear it to work or more sedate socials as it can make you seem way too horny!
Lastly, do not underestimate the socials when it comes to triggering atraction in younger women - They help stimulate the basket of feelings that conspire to full-on attraction and in combination, helps moderate any none you are using. Many effective mixes around younger women are lighter and more socially engaging. As they age, more evert none and high status mixes come to the fore, late 20s/early 30s seems to be a major tipping point.