Did you know that yeast dies from old age too? For consisten results, avoid the packages and jars of yeast sitting on the shelf in the supermarket. Who knows how long they’ve been sitting there.
Buy fresh yeast and keep it in the freezer. I mark the purchase date on the container and replace it after a year. Unless otherwise specified, always use Instant Yeast. I use SAF Instant Yeast from King Arthur Flour.
Even though you store yeast in the freezer, it should be warmed up prior to use. You can dispense the amount you need into a small cup, put the large container back in the freezer, then set the small bowl in a warm spot to come up to temperature. My favorite trick is to soak a washcloth in water and heat it in the microwave for two minutes. I then set the wahscloth on the counter and place the small bowl of yeast on it for about 5 minutes.