The golden rules of coffee
Whichever method you use to brew your morning cup, there are a few "golden rules" that, if followed, will help ensure a good cup every time.
Use good quality coffee
It should be fresh-ideally, no more than a day or two out of the roaster. Alas, few coffee shops can tell you when their coffee was roasted, or even when it was delivered to the shop. The best way to get fresh coffee in Japan is to find a local roaster and buy direct. Failing that, find a shop with high coffee turnover, or one that has a staff knowledgeable about coffee.
Keep the beans in an air-tight glass or ceramic container (or in the original bag if the bag has a one-way valve) and store them in a cool, dry, dark cupboard. Theoretically, properly stored coffee can be kept fresh for 10-13 weeks. Some companies claim that their beans can be kept for up to a year. But, in reality, by the 4th week or so, you'll notice a drop-off in aroma and flavor. Some, if not all, of the flavor-rich oils on dark-roast beans will have disappeared by the 13th week. I leave it to you to imagine what a year-old bean tastes like.
There is some controversy about freezing or refrigerating beans. I don't. Other than ice cream, few foods are enhanced by the freezing process. Freezing can desicate coffee beans and destroy the flavor-rich coffee oils. Coffee beans can also pick up flavors from other foods in your refrigerator or freezer, which can give your morning cup the taste of last night's dinner. (Fish, wasn't it?)
Finally, be sure to use the appropriate roast for your method of preparation. Don't put a light roast in your espresso machine or an espresso roast in your drip filter. And don't use 'ice coffee' beans for anything but ice coffee. It may look like an espresso roast, but it isn't. (Believe me, it really, really isn't.)
Use an appropriate grind for your method of preparation
If you can, grind the whole beans yourself. The minute coffee is ground, it begins to rapidly lose freshness and flavor. (That wonderful smell from a newly opened can of ground coffee? According to rumor, it's injected during production!)
Drip makers and plunger pots, want a medium-to-coarse grind. Espresso machines need a very fine, but not powdery grind. The instructions that come with your brewing equipment or grinder should tell you what grind to use. Many equipment purveyors and coffee roasters will be happy to provide you with a sample of coffee that has been ground to your machine's specifications.
Use clean, fresh water at the appropriate temperature
If your tap water tastes like the bottom of a swimming pool, your coffee will, too. Surprisingly, few people consider the water when they complain about the taste of their coffee. Water quality varies greatly in different parts of the country, but unless you live up in the mountains and draw your drinking water from an artesian well, you may want to use filtered or bottled water. There's no sense in using high quality beans and brewing equipment with low-quality water.
Be sure to use fresh water. This is especially important for those using true espresso machines with refillable water tanks. It is tempting to simply use up the water in the tank before refilling it, but try this experiment: leave a glass of water on the counter for a day or two, then try to drink it. Stale, isn't it? It has something to do with air contacting the water. In the summertime, there might even be a bit of "life" in the form of pond scum floating in it. So rinse out the tank and refill it daily. And clean it with soap and water regularly.
After quality, the next most important characteristic of the water is its brewing temperature. Most brewing methods call for water that is not quite boiling-between 95-98°C (195-200°F). Boiling water can vaporize the flavor-rich oils in the coffee, as well as extract more of the caffeine and bitterness.
If you use a kettle to heat the water, let the water come to a full boil, then turn off the heat for 1 minute. This is generally the amount of time necessary to set up your brewing equipment or perhaps grind the coffee. Be careful not to allow the water to sit for longer than a minute. Water that is too cool will not be able to extract all the flavor in the coffee.
That's it! With very little effort, you are now 90% of the way to a perfect cup of coffee. The other 10%? That will take 90% more effort. And 100% of the next column.