Well, you probably saw this one coming. In its modern all-glass form, the Chemex is coolly insubstantial. It's light and transparent and non-porous. Self-less, if you'll indulge me. Chemex doesn't care to distinguish itself; it would rather distinguish the coffee dripped into it. There are many ways to use it and the last thing I want to do here is delimit what's desirable and what isn't when it comes to using it. Do as you wish, or choose to have nothing at all to do with it. This would be my only instruction--to not take this post as a set of instructions! Not that you would ever commit such a mis-reading, my dear Reader... While I don't want to be too technical and write something that'll be irrelevant to most people, I also don't want to offer platitudes or conventional knowledge that can easily be gotten elsewhere. Hopefully I can hit some happy balance.
* Filters. All sorts of metal filters will work, as will Hario papers and cloths. I'm partial to the standard Chemex-brand filters, specifically the white diamond kind. Diamond, because I find that the square filters can get in the way of the pouring and white because they're less pulpy than the brown. Rinsing the filters will help remove pulpy or dusty tastes and--this is my pet hypothesis--opens up some tiny paths that'll allow small amounts of aroma-enhancing oils through, similar to standard Melitta filters.
* Pouring. A thin-spouted pouring kettle is useful but certainly not necessary. Among many other things, it's a temperature shortcut. After transferring boiling water to a pouring kettle, the water is ready to be poured. One's control is also greatly enhanced, but pouring control isn't as important here as it is with other pour-over methods, since the Chemex filters and the way that they sit against the glass walls pick up a lot of the brewing slack. I prefer to keep my pour in the center and I don't move it around too much; the force of the water does a good enough job of mixing the coffee up.
* Grind. Because drip is obviously gravity-dependent, your grind will depend on your dose. Bigger doses require a coarser grind. If I'm brewing half a liter, I'll use a medium grind, something in between table- and kosher-salt. If you're getting a bitter edge you can coarsen the grind a bit, or you can try pouring less water next time.
* Your timing is similarly dependent on your dose. Making a diner-mug amount of coffee can most deliciously be had with a ~3:00 drip whereas a liter may take ~5:00-6:00. This is hardly ever mentioned: chaff has a big effect. Chaff is that beige flaky stuff, more common in lighter coffees...it's flavorless but it can affect your timing in a significant way, for good or for ill. To reduce chaff, it's best to spoon coffee out of your grinder's bin rather than just dump it straight out of the bin into the Chemex. A lot of the chaff will just stick to the bin's sides.
* Visual cues. You can tell which bits of coffee have steeped more than other bits based on coloring. The whiter/blonder parts of the coffee bed have steeped more than the darker parts. This can help you get a more even pour, not that even-ness is the ultimate mark of quality. I also like to see the grounds thinly and evenly hug the filter after all's said and done.
Looking back on this, there are definitely places where I could have said more and maybe places where I could have said less. Again, my intention was to get at that impossible place between "too much" and "too little." I've also been a little vague about some things because I don't want to imply in any way that I'm interested in dictating how one should use the Chemex. Its exhibition at MOMA is suggestive. Like any work of art, its most resonant meaning comes out of its interaction with people. The Chemex is (nearly) anything you want it to be. It's light and transparent and...