The first step in identifying coffee quality is whether the beans are Robusta or Arabica. Lower quality and/or cheaper brands of coffee have some proportion, if not all, of Robusta beans. Robusta beans produce a more bitter brew with less body. High quality coffees are usually 100% Arabica beans. Check the bag/can of beans you are using. If it uses Arabica beans, it will definitely say so. Many people enjoy coffee made from Robusta beans -- and there's nothing wrong with those beans. However, restaurants generally stick with Arabica beans.
After that fact, the quality of your water and the "cleanliness" of your coffee maker are critical. Use fresh, filtered water when you brew. And make sure you clean your coffee maker on a regular basis with vinegar to remove hard water deposits. And, of course, always wash your filter and coffee pot with soap after each use to ensure that any remaining oils from the previous batch are removed. The residual oil becomes bitter over time.
Then it all becomes a matter of taste! Try different coffee beans from different places. The majority of people find that moderate blends of different beans (a "county blend" or "breakfast blend," with medium roast) are the most palatable. I prefer coffees that are roasted at higher altitudes -- this allows a deep, dark roast without any burnt flavor from the extended roasting process. (Starbucks is roasted in New York...which accounts for the burnt taste.)
Have fun!! Many, many years ago (life before Mommyhood), I was a barista at an independent coffee shop.
