Place your Segovian scales book on a stand or other device where you will be able to easily read it.
Set your timer for two hours. If you do not have a timer, note the time that you start.
Place your guitar in the position that is most comfortable for you to play.Use a posture that will give you the most control. Begin the scales slowly and vigorously. This will strengthen your hand and fingers for later dexterity.
Click on the link under "Resources." It will show you a scale practice pattern developed by Professor Ronald C. Purcell of California State University Northridge. It suggests a time line for Segovian scale playing that helps with finger dexterity. The site also contains a suggestion from Eliot Fisk for right-hand fingering that is phenomenal in developing hand muscle strength.
Continue practicing, increasing the speed and lightness of your fingering as you become familiar with the scales pattern.