When you are planning to reflect on your work, make sure you have a span of time—at least half an hour or more—to settle into the process and “go with the flow” of your thinking. Be aware that reflection is not the time for being judgmental or beating up on yourself: rather, try to describe what is going on in your writing as accurately as you can.
While initial reflection often takes place when you are alone, you may find—as other strong reflective writers have noted—that it helps to share your reflections with others you trust and admire. Even in reflecting, two heads can often be better than one!