With my Kanger tanks, depending on my liquids I use a basic upkeep routine.
1) Every other refill, rinse the heads under warm running tap water, darker and thicker liquids, every refill
2) Every week, heads in service, rinse in warm running tap water, drop them into a cup of everclear or vodka about 20 minutes, then remove, disassemble top air tube, dry burn off the carbon and junk, reassemble, rinse under tap water again, let sit out and air dry, put previous week's cleaned heads back into service
3) Tanks I rinse out every other refill under warm tap water. Tank that has a strong flavor in it, I soak in everclear about 10 minutes, then rinse and shake out before letting it air dry.
I can generally get about 2 to 3 months out of a single head with this method before rebuilding the head or if you are not looking at that technique, replacing the head entirely. Dry burning at least once a week helps prevent the carbon and junk building up and 1) clogging the wick, 2) insulating the coil itself where it doesn't get the liquid up to proper temp or cause an inadvertent coil failure aka popping or melting out your coil. The last, coil melt down, the wire may be reaching proper wattage/temp, but the carbon reflects radiated heat back onto the wire making it hotter and you get a melt down. Dry burning is pretty simple and straight forward.
1) Remove top grommet and air tube
2) Remove top floating flavor wicks off the coil and main wick
3) Fire the coil while blowing on it to keep air moving over it, start at 2 second intervals until any excess liquid is vaporized off, then gradually build up to 4 to 5 second pulses until the coil glows evenly bright orange from center to outer sides, note you might see some darkened wick at the edges of the outer coil, this is normal, darkened wick in the coil itself after the coil is evenly glowing, wick is scorched, head needs rebuild or replacement.
4) Reassemble the head, rinse under tap water to clean out dry residue, let air dry over night on a paper towel or such
5) Fluff up the exposed wick outside the coil chamber when dry
6) Done, coil head ready to be put back into service