Probably the most effective way to remember as much as you can about your labor and the birth of your baby is to try to remain as healthy and rested as possible prior to the start of your labor; this will give you the best chance of staying strong and clear-headed throughout.
Feeling strong and having plenty of energy may also help you remain upright and active during the course of your labor, reducing the need for pain relief such as Demerol (see Tranquilizers), which can sometimes cause memory loss that makes it more difficult to remember the finer details of the birth. It's also helpful to have your birth partner with you throughout your labor so that he or she can help to fill in any blanks later. Photographs and videos are also good prompts.
After the birth, if you find that there are parts you can't remember, you can ask your doctor to let you see your birth notes. You might want to write up your experience in a journal.