Before you start mixing flavors with nic, just use your preferred VG/PG base in small bottles like 5 ml. Experiment with flavors you like and use the calculators for help. That way if your screw up only a small amount of PG/VG is wasted and not any nic. That is how I started and still do it for new flavors, just try them out small before making 30 ml
Have fun!