Some need more, some need less. I started out at 20-30%, but now I like 5-10%. I use Scubabatdans
ejuice calculator spreadsheet and a graduate syringe, so dispensing exact volumes is a snap, and the syringe acts as a mixing vessel for small amounts while you are trying a new flavor recipe. BTW, mint oils like pepermint and menthol generally need only a drop or two for a 6 mL batch, as they are
very strong. Made a 10% peppermint once, and it about blew my head off...sort of like altoids to the fifth power! 8-o