You can do both the material and spiritual squares with a positive affirmation to reinforce the positive qualities of the planet. The affirmation must be precise in the wording, using present tense. The squares may need to be repeated in order to strengthen its positive influence.
Regarding the lunar nodes (North Node and South Node), these are points in the sky and not actual celestial bodies like planets, hence they're not suitable to be created as magickal squares. They represent points where the Moon's orbit intersects the ecliptic (the apparent path of the Sun). The North Node (Rahu) and the South Node (Ketu) are associated with karmic lessons and growth.
The North Node (Rahu) represents the head of the dragon in Vedic astrology and is associated with growth, new experiences, and the fulfillment of desires. It's important to navigate the energy of Rahu with mindfulness, as an excess focus on its desires without consideration can lead to imbalance or unfulfilled expectations. Understanding its placement in your birth chart can offer insights into the areas where you're meant to grow and develop during this lifetime. Integrating the lessons offered by both the North and South Nodes can aid in finding a harmonious and purposeful life path.
The South Node (Ketu) represents the tail of the dragon in Vedic astrology and is associated with karmic influences from past lives. It indicates experiences, habits, and talents that an individual has already mastered or developed in previous incarnations. Consequently, the South Node can point to tendencies or qualities that are familiar or comfortable but might not necessarily be beneficial for growth in the current lifetime.