How is YOUR DIY beginning? share wins, fails, tip and tricks for everyone's success

Hey all, as we are all new here, we are probably all going through much of the same trials and tribulations.
I’m sure we’ve all made our mistakes and maybe even had some spectacular failures (er, learning opportunities). on the other hands, many of us have maybe even come up with a few great ideas.

This seems like the place where we can all share our info, maybe save ourselves and each other from all making those same rookie mistakes on mixing, storage, steeping, layering and flavour development.

for myself, I know that my preferred ratio is 70/30@1% nic, because I don’t yet have the steeping knowledge on how individual flavours develop - every time I get a new batch of flavours, I mix a small batch of every one with 10% flavour (picked up a couple of cases of these for storage:
and every week sample each one and update my notes on how they are developing.

I also use these for rough recipe prototyping (for example 5 drops of vanilla custard, 1 drop of toasted marshmallow, 2 drops of cinnamon danish swirl) and adjust to get a rough flavour profile before I make a full trial batch. for me, it makes things go faster, and can adjust on the fly with little to no waste.

Question - how is everyone else managing their inventories, doing your recipe development, and does anyone have any tips or tricks that they want to share?