-eyes sway around the words trying to understand the essence of the question-
potts_d,
There's a lot of threads out there regarding steeping, and the opinions vary on how and when it should be done, and also the order in which the ingredients should be added to the juice before and after steeping. You can do a search regarding steeping and spend the good portion of an evening hearing of all those opinions.
Thinning the juice is not as big of an issue if you use a heavy VG base, but for me, I don't care for it since the flavor percentage generally needs to be higher. I normally run 85/15 (85% PG / 15% VG) in my mixtures, so any distilled water or ethyl alcohol based flavorings will kill that ratio unlike a PG based flavor. Something to consider when mixing. The lower your VG ratio, the less vapor. Pure PG mixtures will have very little vapor, and if ethyl alcohol based flavorings are used, even less vapor. It will still work in your e-cig, unless it is thinned out too much, thus just creating steam.
My personal recommendation is to steer clear of tinctures and essential oils. I use TA fairly sparingly, it's not water soluble. My atty's last usually 4-6 weeks (even low resistance), and that's just how I vape. Some have reported shorter atomizer life when using oils. That and, who knows how healthy it is to breath in those vapors. It's a personal choice you have to make, but mine is to use only TA. There is of course also Tobacco Extract, which is water soluble. I prefer TA over TE. The taste is a bit better IMO.
As for the main ingredients of the flavors, most of them are made with artificial flavoring molecules. I'm not a flavorist so I don't know the exact science behind it. Some are natural flavorings as well.
To give you a short answer: TA is good. I've not experimented with other tinctures or essential oils. With the wide variety of food grade flavorings out there, I would highly recommend to work with those primarily and enjoy the wonderful world of DIY vaping
