Coffee lovers who create their own blends have less to consider than either commercial or speciality blenders. They should not have to worry too much about consistency, and they cannot use blending to bring the price down much, since most single-origin coffees sold through specialty stores are already premium coffees with premium prices. Blending for price would be like trying to save money by cutting caviar with truffles. Commercial coffee concerns can save money on their blends because they are able to buy large quantities of cheap coffee at bargain prices.
So you will be blending for taste. The way to go about this is simple: Combine coffees that complement one another with qualities the others lack. The world’s oldest and most famous blend, for instance, combines Yemen Mocha and Java. Part of the reason for its fame is tradition. The blend originated when Mocha and Java were the only coffees the world knew. Nevertheless, it embodies the sound principle of balancing extremes or complements. Yemen is an acidy, fruity, winy coffee; Java is rounder and deeper-toned. Together they make a coffee that is both less and more — less striking and distinctive, but more balanced and comprehensive.
The first, pleasurable task in assembling a personal blend is to learn to taste coffee attentively, to distinguish acidity, body, and flavor and some of the more individual quirks: the floral tones of Ethiopia wet-processed coffees, the pungent tones of Sumatras, the dry fruit tones of Kenya. You should also know what qualities you prefer in a coffee and what to blend for. You may simply want an all-around coffee with the best of all worlds, or a heavy, mellow coffee with only a little acidy brightness, or a brisk, light coffee with plenty of body as well.