Be sure that the VG you get is 100% pure, USP, Vegetable glycerin. Some glycerin is animal fat based.
Just a clarification here- many people have used other USP Glycerin, like humco, and have no issue with any damage, or even a single bad thing to say about it. On the other hand, some have an issue with a slight, but noticeable, off-flavor with animal/mixed source glycerin. Humco might work in a pinch, but VG will taste better.
On the other-other hand, PG (propylene glycol) is what most large commercial juices are made from, is thinner, flows better, and tastes slightly sweet. It produces less copious and thinner vapor as well, however.
Personally, I like VG with lorann's flavoring and such and thin it slightly with pure grain alcohol (like Everclear), or even 80proof or higher vodka (Smirnoff is virtually flavorless, just a slight alcohol twang) so it flows nicely. You could also use distilled water instead of the alcohol (cheap, available everywhere), but it will not give you quite the same flavor and you might need more water than you would alcohol.
Vaping zero-nic liquid is really cheap when you make it yourself like this!