Ruth Reichl is the food goddess. I worship her. Here she divulges the secrets of making great lemonade, including using the zest of the lemon and making simple syrup. Also there’s this:
Lemonade takes a lot of juice, so you don’t want to waste a drop. A good juicy lemon will give you a quarter cup of liquid. But they are not all so succulent, and if you have unfortunate lemons you might need to squeeze as many as six to get a cup of juice. Increase your odds by rolling the lemons around on the counter beneath your palm. This will break down the cells inside the fruit and give you more juice. If your lemons seem hard and unforgiving, microwave them for 20 seconds. This will shock them into relaxing, just a little.