To make your own sourdough starter, click this link.
If you have a starter and wish to ensure that your loaves give you a fluffy, delicious result, follow these guidelines. They are most helpful if you keep your starter in the refrigerator.
Mix well to re-incorporate any liquid that has formed on top of your sourdough starter. Whole grain flours especially will yield a darker liquid.
Remove 1/4 cup of sourdough starter from the fridge and place it in a large jar or bowl. Feed the starter with 1 part starter with 1 part water and 2 parts flour. For example, feed 1/4 cup of starter with 1/4 cup of water and a scant 1/2 cup of flour.
Mix the starter, flour and water together and stir vigorously, incorporating plenty of air. Cover the starter with a towel or cheesecloth secured by a rubber band. Leave in a warm spot for 4 to 12 hours until the starter becomes bubbly.
Repeat this process two more times prior to baking using the same ratios listed above.
By the third feeding the starter should be very bubbly and rising to double its size within 8 hours of being fed.
Remember to add some freshly made sourdough starter back to your master sourdough culture.