I've used many things in my prayer life, to remember to pray, to grow stronger in prayer, and to remember the people I'm praying for.
My first prayer journal (above), I started in Sept. 2011 and used till Nov. 2012. I wrote down everything I was praying for that day, everyday (skipping days here and there). When that became tedious, I used it to ponder on Bible verses or in a few cases to release anger by scribbling and/or writing out prayers of "anguish." This is the most filled prayer journal.
I kinda liked writing out prayers, so Nov. 2012 - Dec. 2012, I wrote out my prayers. It worked, in a way, but honestly I kinda slacked off. The next dated thing in it was from Feb. 2013 in which I did verse by verse study of Philemon. (Exciting, right? lol) In Oct. 2013 I used it for Becoming a Young Woman of Faith. In April of 2014 I used it for 30 Days of Love. This has a lot of empty pages still.
My current prayer journal is a much more usable prayer journal. Since July 8th I've written down the names of people I'm praying for, and I've been fairly diligent in remembering to pray for them. I divided the pages with a straight line down the middle, putting the request/person on one side and putting "answered!" on the cases in which they have. Because of this method, I've only used up a couple pages so far.
I've also used a couple prayer devotional books. One I think was 100 ways to Pray or something like that. I've also memorized a prayer from the Bible. I should work on a few more. I memorized Ephesians 3:14-21 a couple years ago. It is a prayer for Spiritual Strength.
I hope one of these ideas may spark your interest and that you would be able to use one in a diligent manner, yet at the same time, I pray it will be from your heart to God.