For a top coil clearo like the iClear 16s keep your PV on its side when you aren't using it to make sure the wick stays wet and/or tilt and twirl it right before you vape. If your juice is too thick to wick well you might need to add a drop or two of distilled water to help it wick better although that is usually an issue with higher VG juices than what you are using.
Once a coil starts delivering a burnt taste you need to clean out the tank and dry burn the coil. I couldn't find a video on how to do that specifically for the iClear 16 but any of the cleaning videos for clearos will give you a good idea of how to do it. Just go easy on the power and stick with no more than 5.5 watts bursts of a second or less once you see the coil start to glow orange