Heres a link to a great article written by Randy Glass.
If your new to espresso you could do a lot worse than to read and understand these principles.
http://home.surewest.net/frcn/Coffee/HowToEspresso.html
If your new to espresso you could do a lot worse than to read and understand these principles.

http://home.surewest.net/frcn/Coffee/HowToEspresso.html