When you're ready to play, each player reads each card and the guidelines, quietly or out loud. Trust your intuition and just play.
Be sure each storyteller gets equal time. If your story goes overtime, and mine doesn't, or the reflections for you last longer than those for me, it's easy to compare. Comparison often brings self judgment.
When listening to the reflections of the seer and witness, we encourage the storyteller to keep eyes closed. This prevents feeling the need to respond directly to each comment and allows the storyteller to focus on whatever jumps out to the storyteller.
Be original in your reflections. Agreeing with what someone else says gives extra weight to the importance of what's being said. One idea is never more important than another through the eyes and ears of the heart.
If you have more than an hour and a half to spend playing Allies, try building in a second round of reflections.
If you're working with a larger group than three, and you have several sets with the same image (i.e. the labyrinth)
you can color code each different set to help people get into groups of three.
With only two people playing, whoever is the seer will also be the witness. You can imagine you're speaking with a great teacher, mentor, archetype, living or not; then imagine them speaking through you.
Here's a taste. Guidelines offer more.