No matter what kind of incident you are involved in - a spat with your ex, an issue about completion of a window-washing job, a dog bite incident - MAKE NOTES. AT THE TIME. IN DETAIL.
Many months will pass between the time of the incident and a any court issues resulting from it. If you make notes about an incident AT THE TIME you will be allowed to refer to them to refresh your memory. This gives you a BIG advantage over the other side, who probably will not have notes.
If you are involved in an ongoing situation (custody, for example; or a large work project) make it a habit to make notes always. Keep a diary.
All I can say is...you (and your lawyer) will be very very glad that you did.