In the first half of this Psalm, David talks about how God speaks to us with His creation. The second half of the Psalm relates to how His written word speaks to us. Both can be just as condeming and heartfelt, but both have different roles to play. The first is all around us reminding us of our creator every moment of every day - yet we still forget! The second half talks about how perfect God's written Word is. Here David has a passion for God's Word and the wisdom His Word provides. David has an obvious love for God's Word and ALL it holds for us:- the wisdom, glory, righteousness, revival...
David sounds like he just wants to continuallly read and discover God's Word. I am in a place, at the moment, that relates to David in this way. I don't seem to have enough time in the day to study God's Word as much as I want to! I want to read more and more, to understand God's plans etc more. The more I learn, and read, the more I want to read and learn. I just want more - more wisdom, more understanding, more knowledge, MORE!!!
David is asking God to make his heart pure so that he is pleasing God for all the right reasons and not for selfish ones. He wants his heart, thoughts etc to be pleasing and acceptable in God's eyes! That should be the prayer we all want to pray - that God can take delight in our thoughts and actions because we aim to please Him!