Simply, if you over-extract, your coffee will taste too strong and bitter. If you under extract, your coffee will taste weak and sour. The goal is to find balance, with the understanding that balance is relative to your particular taste.
Play around to see what you like.
We always weigh our coffee instead of scooping because light roasts and dark roasts have different densities. A general rule of thumb is to use a 16:1 coffee to water ratio. Our cheat is to take the number of ounces of water and multiply that by 1.8. So, if you have 40 ounces of water, you should use roughly 72 grams of coffee to start.
An even and consistent grind will allow for an even and consistent brew.
A blade grinder isn't ideal for in-home grinding. It often results in a mixture of fine powder and large chunks. This makes an even extraction nearly impossible and results in a pot of coffee not living up to its potential.
A burr grinder is for someone who savors coffee and won't settle for anything short of a pure cup. You can widen or narrow the space between the two burrs, giving you control of your coffee. This creates a consistently delightful brew that will seriously impress the guests at your next brunch. It may even get you that nod of approval from your mother-in-law.
Grind size depends on the brew style. Assuming your burr grinder has 10 notches to adjust grind size you would use around a #2 for espresso, a #5 for pour over, #7 for drip, and #9 for French press. These are all rough estimates and you should adjust from here until you find what works best for you!
A good rule of thumb is if you wouldn't drink the water, don't use it to make your coffee.
Water treatment chemicals and naturally occurring minerals will create poor flavors and ruin an otherwise good cup of coffee. The most common and detrimental chemical to flavor is chlorine. We use a carbon filter because it’s very good at removing chlorine, among other chemicals and minerals. The key is to remember to periodically replace the filters to keep them working!
Brew time is dependent on the brew method. As a rough guide, espresso shots should take around 28 seconds, a pour over should take around 2 minutes and 30 seconds, and a French press should take 4 minutes. Times vary for consumer grade drip machines. Adjust the grind size coarser (or higher) to shorten the brew time. Adjust the grinder finer (or lower) to increase brew time.