Here's what makes a noticeable difference, in order of importance:

• Fresh beans: Buy whole beans and grind them yourself if you can. Pre-ground is fine for a week, but after that, it goes flat.
• A consistent grind: You don't need a $300 grinder, but a burr grinder (even a hand one) beats a blade grinder. Aim for table salt texture.
• A scale (optional but nice): You can use a measuring cup, but a scale removes guesswork. Start with 1:16 ratio—30 grams of coffee to 480 grams of water.
• Clean gear: Old coffee oils go rancid. Rinse your brewer and carafe with hot water before you start.

That's it. No special kettles, no exotic water chemistry, no pour patterns that require a barista certificate.