crazy thing....
i tried sucking a lot harder, ie. more air flow, and also sucking a little bit after firing to cool the coil, just as an experiment. also i had a relatively thin wick rolled up inside my coil. 6mls and juice is not darkening and taste is not diminishing!! i haven't looked at the coil/wick yet, because i haven't felt the need to rewick, but i'm pretty sure this is the root of the problem. pretty sure the wick won't be scorched or at least not as scorched.
hooray?
It sounds like maybe you just had too much wick, and that definitely will cause burning. More airflow though, it's not really about "sucking harder", but having more air available near the coil, to cool it -- bigger airflow holes, or more of them. But making the coil skinnier helps in that regard, there's just more "flow," period -- air, juice, etc.
Learning to build coils is really not hard at all -- twisting wire around something, mounting it around screws or thru posts. Getting the proper amount of wick though, that's a true art, and it's just something you have to learn as you go -- and it changes, depending on the inner diameter of the coil. I've finally settled on 3/32 drillbits as the optimum size for the way I vape, and the amount of wick I generally use. But even after building coils and wicking them for well over a year now, sometimes I have too much, and have to yank it out and start over. It should slide easily thru the coil, without "catching"... yet should fill the coil, without any airspace around it.
Andria