Following these guidelines can help ensure the desired results when using dry active yeast.
Start with fresh yeast. It has a very short life span. Buy small amounts and always check the expiration date before using.
If you refrigerate yeast, always allow it to return to room temperature before adding it to water.
The water temperature in which the yeast is activated is very important. Too hot, and the yeast may be killed (it is a living, single-cell organism). Too cold, and it doesn't respond. An instant-read thermometer is a necessity. The temperature should be between 105 and 115 degrees F.
Use the correct amount. Most packaging includes simple measurement conversion information.
Allow yeast dough to rise in a draft-free area that is between 70 and 85 degrees F.