Yeah Wizard. That should be a rule of thumb, and part of the DIY guide. VG based liquid,
buy your nic in VG. PG based,
buy it in PG. You just open your options to better tweaking if you have the correct base to begin with. I think it's quite impossible, for me at least, it's impossible to do a 24mg nic solution if I want 30pg 70vg. I could come close, if I don't have any flavor at all, but it can't be done.
edit:
I guess getting nic in 100mg helps to open the options too. I have 60mg, but even with 100 I can only have a top 6 percent flavor with my scenario above.