Don’t be afraid to pre-mix flavor concentrates for your favorite juices. Perhaps 15ml at a time is sufficient. Then when you go to mix the next batch, simply add whatever percent of the pre-mix represents the entire flavor portion of the mix. Example - I have one that uses 6 flavors. I mix those flavors together and store. When I make a new batch I add my nic, vg and pg and then 21% of the pre-mix. Perfect every time.
Don’t forget to clean mixing implements such as syringes, droppers, pipettes etc. Some of the concentrates, especially with plastic pipettes - will get embedded into the plastic and sully your next mix. Nothing tastes worse than espresso and peaches.
Don’t be afraid to experiment. On ECF one of the members has what he calls the 100 drop test. That is where the percentage of each ingredient is used in a test batch where each percent equals 1 drop. I use this all the time with glass droppers…although I never measure my base liquids anymore…they are always around 2.5 ml which is close enough to start with. Then for example if I have 2% strawberry, I add 2 drops. For 5% custard, 5 drops and so on. This saves time and supplies, mixes very quickly with just a few shakes, and allows you to test very quickly…in minutes. Credit to Bill’s Magic Vapor on ECF