A meditation journal can help you keep track of your meditation practice over the years and help you understand how your meditation is going for you. First you will need one sturdy notebook. Things you might want to include in a meditation journal include:
-General comments like about a local charity, an event in today's news or something from your life; books or films you have read or seen. Also poetry you have written or by other people.
-Mantras, chants or hymns you use in your spiritual practice.
-Prayers you have said and answered prayers. George Washington was said to have kept a daily journal of all his prayers which can currently be viewed through the library of Congress.
-Topics covered in your meditation.
-Notes on Dharma talks, Buddhist books and texts
-Excerpts from Dharma texts that our relevant to your current situation.
-Dharma passages, what they mean and how you can apply them to your life.
-Definitions-of words that come up in your spiritual practice
-Questions or concerns about your spiritual practice or teachings.
-Talk about people who give you inspiration.
-New insights you have had about your life or the world in general.
Basically there are no limits to what you can put in a meditation journal.