Once you've found the ratio, think about what it means for you.

Higher VG, like 70/30 or 80/20, means thicker liquid. That translates to bigger clouds and a smoother inhale. If you're using a sub-ohm tank or a rebuildable atomizer, this is your sweet spot. The coils can handle the thickness, and you get the dense vapor you're after.

Higher PG, like 50/50 or 60/40, is thinner and carries flavor more efficiently. It also gives a stronger throat hit, which many ex-smokers prefer because it mimics the sensation of a cigarette. Pod systems and smaller devices work best here because the thinner liquid wicks easily and doesn't gunk up the coil as fast.

There's also the question of nicotine salts. If you're using salts, you're almost certainly in a pod or a low-wattage device, and you'll want a higher PG ratio. Salts are designed for that setup, and high VG can cause dry hits.