I have an overall recipe I use for all TPA based liquids and it seems to work well except for a few flavors. I always make 3ml batches(or approximately). Always 2.7ml of pg/vg. For instance my base flavor is always 6 or 9 drops. and then the add-in flavors are always 3 drops, never adding more than 18 drops of total flavoring. Koolada is always 3 drops, sweetener always 3 drops, if using a combo of sweetener and sour I use 3 sweet and 5 sour. Here is my favorite recipe 2.7ml pg/vg, 9 drops cotton candy, 3 drops sweetener, 3 drops Koolada, 3 drops lemon. I hope my drops% makes
sense. I found that a few flavors require 12 drops which are mango, granny smith apple, strawberry, green tea, dragon fruit i am sure there are a few others but off the top those are the ones I can think of. The ones I only use 6 drops with are any mints, menthols, cloves or cinnamons(except cinnomon roll), chai tea, mocha, peanut butter, coconut extra(1drop is enough to any 3ml mix), maple syrup, pecan, maraschino cherry, apple pie(the crust flavoring is strong) again those are the stronger side ones that i can think of. I just always keep in mind to never add more than the 18 drops per 3ml's. If you practice using the TPA flavorings you will learn your own ratio that will work for most of the flavors and make them to your liking.