Flavor is subjective. I start with 15% and go from there, some flavors require more some less. Most of my flavorings are from Capella's, only my opinion. Do small batches of whatever you're trying to make, that way you don't waste much nic or additives (pg/vg). Personally haven't had much luck with the others, so I can't really give an opinion on them. But like I said, Flavor is subjective, what is good for me may not be for you. And start simple, one or two flavors at a time, then you can work from there. Some suggest starting at 10%, it's really up to you. Hope that helps