1. Using Boiling Water
When you use boiling water to brew coffee, it extracts bitterness and acidity from the beans. The ideal temperature for brewing is actually around 200 degrees Fahrenheit (93 degrees Celsius). If you want to try this out, an easy way to get this temperature is to boil water and then let it cool for about a minute.
2. Using Too Much or Too Little Coffee
How much coffee should you be using? The "perfect" ratio is 2 tablespoons of coffee grounds for every 6 ounces of water.
3. Buying Pre-Ground Beans
Sure, pre-ground beans are more convenient, but once coffee beans are ground they immediately start to lose their freshness. Buy grinding the beans right before you use them, you'll get a fresher cup of coffee.
4. Using the Wrong Grind
Different coffee equipment requires different grinds. Fine grinds are for espresso or aeropress machines, medium are for drip makers, and coarse are for a french press.
5. Storing Coffee Beans in the Freezer or Refrigerator
Roasted beans have tons of holes in them, so they will absorb moisture and smells from other foods in the fridge. Instead of storing beans in the refrigerator or freezer, keep them at room temperature in an air-tight container to preserve freshness.