Coffee to Water Ratio: Start with 1 tablespoon of coffee to every 6 ounces of water. From that point you can experiment to find the right ratio for you.
Water Quality: Chemicals like chlorine in tap water can greatly affect your coffee’s flavor. Try using filtered or spring water (from a glass bottle), never use distilled! Distilled water is missing certain minerals that make water more palatable to drink.
Burr Grinders vs. Blade Grinders: Grind your coffee fresh, at home, with a burr grinder. Burr grinders grind the coffee by forcing the coffee between burrs so the coffee is only ground once. Blade grinders continually grind and re-grind your coffee, giving you some particles that are super-fine like dust while other particles will be larger. This causes the powder-like coffee to over-extract and gives you a noticeable bitterness in the cup.