Interesting question. I have found that some liquids change daily during the steeping process. I shake, take the cap off and sniff each day. Then all of a sudden, perhaps dramatically, one day it smells great where the day before it was not smelling so good. I don't vape something until it smells "right" if that makes sense. My sense of smell goes hand-in-hand with my tastebuds. If I have a stuffy nose then the flavors won't taste right. Also, depending on what I just ate, or drank, the vape flavors change throughout the day! Some days, a simple drink of coke or pepsi is WAY too sweet and I have to dilute with club soda or seltzer water. Other days I can drink it straight up

LOL (same is true with coffee...I like it dark anad strong with just a touch of cream and sugar, yet some days even though I brew it identically every day...I have to add more or less cream and sugar. Go figure
As others have said, drink lots of water to stay hydrated. Hydration is a big factor!
One more thing...I've had juices that are great for a week or so, then all of a sudden the flavor is gone. I'm guessing some flavors just evaporate? Or, all of the flavor was at the "top" and I didn't shake the heck out of it enough to blend it before vaping for the first few days?

Vaping is a lengthy learning process as well as the "quit smoking" side affects.
Good luck! I hope you get it figured out
