Keeping a prayer journal/diary is like writing any other personal diary, except that it tends to be more focused and have a clearer purpose. A traditional diary can sometimes become rather introverted and self-indulgent! In a prayer diary you write about your daily experiences in the form of prayer.
e.g. ‘Dear Lord (rather than ‘Dear Diary’!), thanks for the nice weather today, and for the chance to do particular activity. I’m worried about name, please help them with particular problem and help me to know what to do to help. I’ve been finding difficult task hard at work at recently, please provide some help for me…etc.’
There may be ongoing situations written on one page of your diary to refer to generally.
I kept a prayer diary over some years, using it every few weeks. Every so often I would go back to read over my thoughts and prayers, and make a note of answered prayers by drawing a smiley face next to my original requests. I would then draw a face with a wiggly mouth next to those prayers that were still awaiting answers, and a surprised face next to the ones, which had been answered in surprising ways! It was always fascinating and encouraging to look back. It also reminded me to thank God for answering prayers: sometimes I had forgotten to do so. You might devise a different system for making a note of answered prayers.
This idea can also be used at home or in prayer groups for members’ prayer needs, and similarly looked back upon, as a record of answered prayers.