Sit or stand in front of a mirror.
Shuffle your deck as you gaze at yourself, at your own face, eyes, mouth, body, posture, clothes in the mirror.
Gaze until you become almost a stranger to yourself. Cut the deck an odd number of times–settle on how many before you begin–and draw the top card.
Now, if it is a major arcana or court card, imagine that you are the embodiment of that card. You in the mirror, the incarnated Empress, the living archetype of the Star, the Page of Swords, etc. What would you look like? How would your posture, expression, bearing, attitude be changed? What would you say to yourself in the mirror as that character? What advice does the new you have to give the old you? What do you look like, how do you hold yourself? What are your surroundings? What stories do you have to share? What life lessons, advice? What talking to can this archetype give to your old self? Perhaps say those things aloud before writing them down. Change your accent, the pace of your speech. Perhaps really move your body as the archetype might: leap as the Fool, or utilize an object as the Magician.
If it is a minor arcana card, imagine that you are embodying an action the card represents: traveling, resting, cultivating, etc. Describe yourself as if you were engaging in the activity. Visualize yourself in the scene of action on the card. What are you feeling, sensing, seeing? How would your body be moving? What are your motivations? What would you learn from the activity?
Allow yourself to get lost in the scene and move your body. Lounge as the 4 of disks encourages, or bear the heavy load of the 7 of swords. Immerse yourself in the scene of action–let all the poem flow from a place of action represented by the card–including inaction.
For either scenario, let the colors, symbols, numerology, astrology of the card dictate the pace, diction, form, of the poem, if those limits help you begin or continue. Whatever keeps you in the flow.