I’m getting e-liquid leaking through the airflow

Try the following:

Make sure it hasn’t been left in a hot place causing the device to overheat and the e-liquid to thin.
Check to see if the coil needs replacing (if it does, make sure you always follow our coil priming guide).
Make sure the coil is securely tightened and not cross threaded.
Check that any O-rings on the coil are in place (check a new coil to see how these might look).
Examine how you’re vaping - if your device is designed for Direct-To-Lung vaping, but you’re Mouth-To-Lung vaping, you may be causing the device to overheat.
Check what e-liquid you’re using. If your coil is low resistance then it has bigger airflow holes which are designed for use with higher VG (thicker) vape juice. If your eliquid contains too much PG (thinner) then it can end up leaking out of the airflow.
Increase your power setting to vaporise more juice per puff and prevent leakage from a flooded coil.
Empty your tank before getting on a plane! If you’ve recently taken a flight, the change in air pressure will force your vape juice out of the tank.