‘Priming’ means preparing the coil for use so that the cotton inside doesn’t burn the first time the device is used after filling.
To do this, just drop e-liquid into the little circles around the sides of the coil. Do this as much as you can so that the cotton soaks up as much e-liquid as possible. Next, fill the tank and once it’s filled let the tank sit for at least one minute to let the e-liquid soak further. Next, break in the coil by turning on the unit and setting the wattage to the lowest it goes. Fire the unit for a couple of seconds, then increase the wattage and fire again. Keep doing this until you reach your ideal wattage and then begin vaping.
NOTE: Some units don’t start at 1W (e.g. the Polaris Vape Pen Mini is set on 30W and cannot be adjusted), so they need to be ‘pulsed’ during priming.