From Head to Toe

练功先练桩，大鼎增力量

One shall first train pillars when training skills, upside-down adds strength

Training pillars to first fix one's posture.

Full and Keeping One's Cool

內實精神，外示安儀。

內 inside, inner part, internal

實 full

精 essence

神 spirit

精神 vitality

外 outer, external

示 show

安 peaceful, at ease, undisturbed

儀 appearance, bearing

Don't Open the Door!

開門閉戶，陰衰陽興。

開 to open

門 door(s), outer door(s)

閉 to close

戶 door, inner door

陰 Feminine principle

衰 to decline, to become weak

陽 Masculine principle

興 to prosper, to flourish 

Changing Doors

One of the eldest texts known describing the martial arts theory is called "The Lady of Yue Talks About Fencing", a passage from the historical records called "Spring and Autumn Annals of Wu and Yue" written by Zhao Ye (?-around 83 A.C.). Later literary works inspired by this lady fencer figure, such as the one of the famous Hong-Kong writer Jin Yong called "Sword of the Yue Maiden" has made this passage quite famous, more than the one about archery that follows a few paragraphs later. Indeed, introducing a lady fencer in a male chauvinistic society which forbade teaching girls because they would marry into another family and having her teacher being an ape, a white gibbon, cannot but struck one's imagination.

Roots

打拳不遛腿，必是冒失鬼

Training boxing without strolling with the legs, certainly a reckless person.

Or

Training boxing without stopping on the legs, certainly a reckless person.

Legs and up to the waist are the roots, the essential part of training.