Use the paint in a bottle with the brush-- not the pens.
Brush a little inside the neck-- once it's in the flame and up to temp the paint turns a dark gray -- that's when you stop heating. The paint turns to an ash like substance and brushes out easily with a bronze or nylon brush in 1 or 2 strokes. I use it on about 5 cases until I get my timing set right-- then just leave the speed and flame alone while I do that batch of cases.
Do some homework on temps-- most guys run the 700,750,800,or850 paint-- you'll have to decide what's right for you.
Some guys also use a lower temp paint near the head-- but I've never had any issues with heat migrating towards the head. Some guys drop into water- I've never used that method either. You'll have to decide what's right for you as there serm to be several thoughts on what is the right way.