Always secure the negative wires (non ceramic side, black nut, white nut on Herc) first.
Don't turn on auto-feed unless using 100% vg and even then you can leave it off.
The
juice feed is controlled by the mouthpiece itself, turning it clockwise will close the feed, cc will open it.
Make sure the knurled 'sleeve' that holds the coil assembly etc is tightly secured into its respective place or else closing the
juice control too tightly when filling can cause the whole assembly to unscrew when it is reopened.
The mix of the juice will determine how much to open the juice control, obv thinner juice will require less turns of the tip, thicker juices will require quite a few turns to expose enough wick.
It will also depend on what type of wick you're using, running cotton seems to increase wicking, and reduce amount you have to open the feed.
Worst case keep opening it up until you get a slight gurgle then close it down some and allow the excess to burn off naturally, then you should be good.
Always close the juice feed when filling just to be safe, also be aware that removing the top nut with the tip o-ring has a tendency to unscrew the chimney/feed so keep an eye on that.