Next, the extraction itself. Time matters, and so does the coffee-to-water ratio. A standard espresso is 1:2—say, 18g in, 36g out. If you're doing 1:3 or more, you're diluting the aroma. Tighten it up. And water temperature? It should be between 195–205°F (90–96°C). Too cold, and you won't extract the fragrant oils. Too hot, and you'll burn off the delicate notes. If your machine doesn't have a temp gauge, try preheating your portafilter and cup, and run a blank shot to warm the group head.