When I meditate, I like using the tree as a metaphor in my practice and have since at least a decade. Here is how I do it. First, sit down on the floor in silence, or with soft music. Let the palms of your hands rest on your knees facing upward. Our palms are centers of energy, to give and to receive, and it's though the various mudras, both Yoga and Qigong practitioners, can direct energy. Letting your palms face up, enable you to receive energy. Inhale through your nose, and exhale through your mouth (or use only the nose if you prefer yoga style).
Start by grounding yourself. Feel the floor beneath your seat and visualise how roots go down under you and into the earth. As if you would be a tree. Feel a safe connection to Mother Earth.
Then, open up your crown chakra and let golden light enter through you, like a tree receives sunlight. Visualise a beam, a ray, reaching into you directly. Fill yourself. Feel rejuvenated in connection to Father Sky.
Finally, find presence in your heart. Seek humility and compassion, and let this expand into the world.
Photo by Richard Laitila at Honolulu Design Center 2010.