Interesting excerpt from the Nei Jing (Chinese medical / taoist classic)

...those who follow the Way [i.e. taoists], they can drive away old age and they preserve their physical appearance.

...They upheld the patterns of heaven and earth and they grasped the regularity of yin and yang.
They exhaled and inhaled essence qi. They stood for themselves and guarded their spirit. Muscles and flesh were like one.
Hence, they were able to achieve longevity, in correspondence with heaven and earth. There was no point in time when their life could have come to an end. Such was their life in the Way.

...They were of pure virtue and they were entirely in accord with the Way. They adapted themselves to the regularity of yin and yang and they lived in harmony with the four seasons.
They left the world and they departed from the common. They accumulated essence and preserved their spirit. They roamed between heaven and earth and their vision as well as their hearing went beyond the eight reaches. This way, they added to their lifespan and were strong.

...Next, there were the sages. They lived in harmony with heaven and earth and they followed the patterns of the eight winds.
They accomodated their cravings and their desires within the world and the common and their heart knew no anger.
...They made every effort to achieve peaceful relaxation and they considered self-realization as success. Their physical body did not deteriorate and their essence and their spirit did not dissipate.
I put some phrases in bold for emphasis the essential parts which are - according to my current knowledge - important to be followed. I'll take later time to explain all of them, but at the beginning I start with the simple things:

Essence, in Chinese jing, is the closest to the physical body energy which sustains its functions. It is different, more gross I'd say, energy than qi is, which in turn is the universal energy for body closer to astral and can be untilized in many ways, starting from mental or emotional, to finally physical transformation.

Yin and Yang - are the most general "keys" to be watched on the way to the immortality. They are maybe too general in practice, but are good references. Heaven (cosmos) and Earth (matter) are basically also yang and yin, respectively, however they are seperate because they are manifested yang and yin (in opposite to unmanifested polars).

I already talked about the importance of spirit (or shen energy in TCM) before - the Chinese book uses the term of "preservence", which I refer to as "connection", but the idea is the same: loosing the spirit frequency disconnects us from the source of life / our original frequency. Spirit frequency is then kept in body.

Eight winds refer to the 8 world directions or 8 fundamental cosmic energies present on the Earth. They must be balanced, just like wu-xing (5 elements).