This article is part of CNN Underscored’s Guide to Coffee, a two-week focus on everything coffee, from the best methods for brewing it to the best machines to do so and the accessories and gear you ...

Pair a $5,000 chromed-out Italian espresso machine with old or poorly ground coffee, and your ristretto will taste mediocre — or worse, like a cup of salty battery acid. But invest in a good manual ...