In my opinion, which I believe does come from experience, I would recommend mixing 1/2 cup of kava with 1.5 cups of room temperature water and 1.5 cups of boiling water.
Mix a tablespoon of soy lecithin with the boiling water. Pour the kava into the cold water and then add the boiling water to it. Mix it for about five minutes. Then let it sit for about a half-hour. Then, toss it all into a double-layer of paint strainers and squeeze it all. After squeezing it for about another five minutes, pour it all into the blender and blend on high for a minute, and then pour that into the paint strainers, that you've rinsed in the mean time, and squeeze for another five minutes. Strain it through a single paint strainer that you've held aside for this purpose, and then finally through a Fijian strainer bag.
This is a very thick grog, thicker than what I normally drink, and is a great way to increase your cost-per-shell, but it also overloads your system.
When your eyes can't focus any longer, then make a normal "thin" grog.