How I've been doing it.
I use a gallon pitcher. Fill it with 2 cups of what ever ground coffee you like. Then a gallon of water. Leave it out in room temp for 24 hours. Leaving it out to steep is better - if you put it in the fridge to steep it tastes more acidic.
The next step I've done in two ways:
1. Get a 2nd gallon pitcher and a nut bag (https://www.amazon.com/gp/redirect.html?ie=UTF8&lo...
). Empty pitcher 1 into pitcher 2 through the nut bag. Refrigerate.
2. Put pitcher 1 in the fridge after the 24 hour room temp. Then just use a single-serve coffee thingy with paper cone filter if you want to to it by cup.
I've gotten lazy and have been doing the 2nd method lately. I usually fill up a bunch of mason jars and leave them all in the fridge and grab one as I leave the house in the morning.
I've been using ground coffee from Trader Joe's. Obviously you'll have to experiment a little with whatever brand you pick.