I'll put this one in the strange thing I learned here:
I am using cotton for wicks and was changing them every two to three days as they were getting pretty gunky, then read that if you turn the voltage up it will vaporize the liquid instead of boiling it. Now this may seem obvious but I was thinking that since my wicks were cotton I should use a lower voltage as to not burn it. Wrong. Cotton is actually very resilient and absorbent. When using a lower voltage the juice would boil instead of vaporize and so would leave a lot of residue behind causing a gunky mess. Now I am running around 4 to 4.4 volts on my builds (1.6 - 2.0 Ohm) and finding that my coils and wicks are staying clean and producing better vapor. Along the same line tightly packed coils (vs loose wraps) perform better and stay "gunk" free longer. So thanks to where ever I read that here on ECF as my coils now last longer than I have patience, I always end up rebuilding them because I like to instead of having to.