My yantra teachers have taught me to always start with Ganesha, the remover of obstacles. Ganesha is the god that represents the beginning of things. The associated mantra is:
Om gang ganapataye namaha
The colors and shapes represent the wood production cycle. We start with the green wood, then red fire, and then the center with the yellow earth. Because Ganesha is ideal when starting new things, I relate this yantra to the Zhen/New beginnings gua (area of the Bagua, the Feng Shui Map), and the element of wood.
Ganesha also had his head cut off by his father Shiva, while protecting his mother Parvati. Similar to Chinnamasta, Ganesha became enlightened when his head was cut off, and he was able to see that he was the same as his mother and father. Therefore resolving family issues. Which again brings us back to Zhen.
As a feng shui adjustment, the Ganesha yantra may be placed in the Zhen area of your home, office or bedroom for assistance in starting new endeavors or family issues.