For a long time now, I have been making my own e liquid. I make a base at 18mg (1.8%) with no flavour and with about 70 - 80% glycerine. I find PG makes me cough and gives me a gravelly throat.
I add concentrate flavour only when the e liquid is in my tank. I'm a tank person. So I know how many drops to add for each size tank. This varies from 6 - 12 drops. And even flavours differ.
I usually drip bought e liquid.
I find most e liquid has a very strong flavour just vaped straight off in a tank. And they are heavy for an all day vape flavour. But I have come to a wonderful discovery!
There are some flavours I reely reely (to quote Darren) like! So I add them to my base e liquid in my tanks. I get the flavour loud and clear - but not too strong - and it's wonderful for an all day vape. I have to tip my tank and twirl it a bit to mix it well.
Furthermore, my coconut, almond and coffee concentrate is totally without sweetness, so if I am using them, I add a few drops of my bought e liquid too. It just sweetens the mix.
A consideration is that adding concentrate dilutes the nicotine strength, so I buy my sweetness flavours in 24mg (2.4%) so with the concentrate diluting my mixture, the 24mg drops just pushes it back up. So far, this is working beautifully.
I just got vapemail yesterday - new tanks, and TJuice from Alston Moore E-Cig Shop. My "sweetness" flavours are Java Juice and Vamp Vape. Java Juice is a sweet coffee with a great flavour that makes my unsweet coffee good. Vamp Vape is a sweet caramel with a hint of coconut - so for my Almond and Coconut, it works!
Smoking was never such fun.