First decide the percentage of flavor you want to use or is recommended, then just take the percentages and multiply each by the % of flavor you want to start with. Let's say 20% flavor...
37.5 X 20% = 7.5%
25 X 20% = 5%
12.5 X 20% = 2.5%
and so on for each flavor.
I would use the same size dropper for everything. Start with a small (3ml) test batch at the lowest % you think you'd like. You can always add more, but it's difficult to fix a mix with too much flavor.
Once you've found your 'sweet spot' for this (or any) flavor, and if it's a recipe you think you'll use a lot of, just make up a bottle of flavor base at your desired percentage to mix into your nic/VG/PG base as needed.
I think what I will do is make up a base then try that @ 10, 15 and 20 %. My first try was 15%.
As a relative newbie, I am still trying to figure out my mod too.
I have a bullet stacked @ 6V and 3 ohms. I needed the kick to get my off the analogs but now I am thinking I want something with less watts. I might step down to 3.7 V and some LR Cartos. If that does not work then I will likely get a VV.
I tried this mix with an Atty, for some reason Atty's taste muted to me, I really like the Carto in my tank better for draw and flavor.