All my flavor concentrates are in the kitchen in bins, along with my working nicotine, pg, and vg.. The extra nicotine is kept in the freezer in glass bottles, as is the extra PG and VG (those are in plastic jugs).
I'm a strong advocate for safety and believe nicotine should only be stored under lock. I use an approach I believe is effective, convenient, and low-cost. Here's a link to what I use. Enjoy!