Roast level is the first clue. Light roasts keep bright, fruity and floral notes from the bean. Medium roasts balance sweetness and body. Dark roasts bring cocoa, smoke and a heavier feel.
Origin shapes flavor too. As a rough guide, many East African coffees lean bright and fruity, Central and South American coffees lean nutty and chocolatey, and Indonesian coffees are often earthy and full-bodied.
The process line matters more than most people think. Washed coffees taste clean and crisp. Natural coffees, dried inside the fruit, taste sweeter and jammier. Honey process sits in between.
Look for a roast date, not just a best-by date. Most coffee tastes its best from a few days to about four weeks after roasting.
Keep beans in an airtight container away from light and heat. The fridge is not your friend here, since moisture and odors creep in.