I have recently read a book that has answered many questions I have had over the year about praying... funny how something that is essential can be so difficult sometimes. This book has helped me gain perspective to help me determine my heart, motives and to fully understand God's love for me and His openness to hearing my requests, and praises, from His throne of Grace. If this is something you have struggled with too, here is the title and author:
Prayers God Must Answer: Take Your Case to God...and Win
by Voyle Glover (Author)