One essential thing for a meditator who starts out on the meditators path, is to keep (or create) a meditation diary. This website, but more so my book (can be found here), may be seen as one example of a meditation diary. Thus it could serve as a general framework for the creation of a meditation diary of a practitioner interested in comprehending the Abhidhamma.
Keeping a meditation diary will help the meditator to keep track of his progress. It will keep him motivated to try hard to discover new things in his meditation, and it will help him to remember his insights and later to intelligently order them along definite lines, as shown throughout my book.
For a meditator the essential thing is personal experience. There will always be things pressing on him to accomplish something outside of himself. So keeping a diary will help to build up some pressure to accomplish something inside instead.
But in order to be able to write about one’s personal experiences, one has to learn to name what one experiences. Thus a meditation diary also will have to capture some theoretical knowledge.
Hence should a meditation diary best be divided into a theoretical part, which gradually becomes modified to one’s own understanding of principles. And a practical part proper. That is, a record of specific personal experiences and experiments, which will gradually be seeked to be perfected. Such part will usually start off with simple experiences, which yet have been perceived as somewhat magical or significant. But as more special experiences are gained and captured, naturally some of the very simple ones will loose their significance and might be removed or marked as unimportant.