At the top of our asking in prayer is asking for the Holy Spirit.  We are in constant need of being filled afresh and anew with the Spirit.  Our prayer life can degenerate into asking for things.  He is to be at the top of our asking, seeking and knocking.  The idea conveyed in Luke 11 is that this is not casual asking but it is serious-soul-hunger asking, a deep inner yearning.  T.W. Willingham once said, “It is unthinkable to me that God would give His Spirit to anyone that did not want the Spirit more than they wanted a new car or a new television set.”  

“So I say to you: Ask and it will be given to you; seek and you will find; knock and the door will be opened to you.  For everyone who asks receives; he who seeks finds; and to him who knocks, the door will be opened. Which of you fathers, if your son asks for a fish, will give him a snake instead?  Or if he asks for an egg, will give him a scorpion?  If you then, though you are evil, know how to give good gifts to your children, how much more will your Father in heaven give the Holy Spirit to those who ask him!” Luke 11:9-13 (NIV)