1. Start with a grind size around that of coarse sugar.
How much: Most pourover drippers work best when they're between one half to two-thirds full of coffee grounds. Any less than that, and there won't be enough coffee to restrict the flow. Any more, and your dripper may overflow. You'll also want to make sure you're dripping into a large enough vessel. If you're the more precise-measurement type, a good coffee-to-water ratio is between 60-70 grams of coffee per liter of water (a mass ratio between 1:16 and 1:14.)
2. Get your clean (filtered if you need it) brew water ready. You'll be using water that's about 30 seconds off boil if you're pouring straight out of your boiling kettle, or immediately off boil if you're pouring into a second pouring kettle. I like about 207°F for medium to light roasts, and about 10° lower for dark roasts.
3. Start your clock and add enough water to soak all of the coffee (a little premature dripping is okay). Wait for the coffee bed to stop the initial swelling (about 30 seconds) before adding more water.
4. Continue your brew. Try to pour quickly, gently, and evenly across the surface of the coffee, pausing between pours to pace your brew to your target brew time (see below). The distance that your brew water drops can affect brew temperatures, as well as increase or decrease the amount of agitation that the falling water creates wherever it falls in the coffee bed. In general, the lower you pour from, the better, if for no other reason than it's the easiest to create and maintain consistency.
When you stop adding water, your dripper will continue to drip for between 20 and 60 seconds.
Your target total brew time is about 2.5 to 3 minutes for dark roasted coffee, and 3 to 4 minutes for medium to light roasted coffees. This includes the dripping time after you stop adding water.
Make adjustments! If your coffee tastes weak, you're probably grinding too coarse, so try a finer grind the next time around. If your coffee tastes too strong, next time use a little less coffee, or just add a bit of hot water to the finished brew to taste.
source : seriousseats