70% vg is my preferred ratio, nice and smooth with just a bit of throat hit from the pg. The VTC is a great unit, 50 watt unit correct? 12 mg is very strong, but if you prefer the higher nic juices, you should cut back on your airflow and run an 'above-ohm' coil, 1.2 - 1.8 ohms for a mouth to a lung, cigarette style draw and stay at lower wattage. I run 1.5-3 mg juice, which is pretty much mandatory if you want to run higher wattage and get big time flavour. On my big setup my 'sweet spot' is 85-100 watts with the airflow wide open, and 45-55 on my smaller setup. With 12 mg juice that would put me on the floor lol