So, the version I'm going to be using as a basis is the one by Gia-fu Feng, but cross-referenced from time to time to others...
The first chapter says:
The Tao that can be told is not the eternal Tao.
The name that can be named is not the eternal name.
The nameless is the beginning of heaven and earth.
The named is the mother of the ten thousand things.
Ever desireless, one can see the mystery.
Ever desiring, one can see the manifestations.
These two spring from the same source but differ in name;
this appears as darkness .
Dakness within darkness.
The gate to all mystery
 Legge has 'trodden', but D. C. Lau has 'spoken of' and John C. H. Wu has 'talked about'
 Lau has 'constant'
 Lau has - brilliantly, I think -
'Hence always rid yourself of desires in order to observe its secrets
But always allow yourself to have desires in order to observe its manifestations'
 Both Lau and Wu have 'mystery'. Lau says:
'These two are the same
But diverge in name as they issue forth.
Being the same they are called mysteries,
Mystery upon mystery -
The gateway of the manifold secrets.'
Richard Wilhelm's version of this chapter is interesting. He gives:
The DAO that can be expressed
is not the eternal DAO.
The name that can be named
is not the eternal name.
'Non-existence' I call the beginning of Heaven and Earth.
'Existence' I call the mother of individual beings.
Therefore does the direction toward non-existence
lead to the sight of the miraculous essence,
The direction towards existence
to the sight of spatial limitations.
Both are one in origin
and differ only in name.
In its unity it's called the secret.
The secret's still deeper secret
is the gateway through which all miracles emerge.
I have two commentaries on the text, one by Wang Pi (226-249CE), and one by the taichi master and polymath Cheng Man-ch'ing (1901-1975)... Wang's is regarded as the commentary, though many seem to 'hae their doots'. I will try and base my own observations around both of these plus what I myself have managed to glean from the school of hard knocks.
The apparent focus of the Tao Teh Ching (as opposed to that of the Ch'uang-tzu which concentrates exclusively on self-development) is the learning of good government in accord with the Tao... This is somewhat misleading on one level, because - for good government to exist at all, the first thing needed is good governors... The Tao Teh Ching is NOT a political breviary, as are, for example the Confucius and Mencius, but is rather a text on what the Tao is, and how one might accord oneself with it, thereby engaging in good governance as a byproduct. This is important.
Thus the text opens - at least in the form that has come down to us as the Tao Teh Ching; there is another, the Teh Tao Ching or Ma wang tui text, where the first (chs. 1-37) and second sections (chs 38-79) are reversed - with a description of what the Tao is not...
First and foremost, it is not conceivable - you can have no ideas about what it really is at all - and it is beyond all expression. As Wang Pi points out, "the Tao that can be rendered in language and the name that can be given it point to a thing/matter or reproduce a form", neither of which is consistent with it...
We are talking here about the secret of secrets, the source of all mystery, the sorurce of the source of both being and not being as it were.
The Taoists consider than anything that exists has its source on non-being and that even non-being is mere a name for something of which we can have only the vaguest idea... an idea being inherently intellectual, after all.
The Tao as mother, source and root transcends all ideas and concepts...
This 'emptiness' is not a blank 'nothing', but rather an eternally fountaining plenum creating its myriad displays in every tiniest fraction of the pico and femto second...
The display that is both very much 'there' and yet, ultimately, not at all what it seems...
Study of emptiness stems from stilling the 'monkey mind' with its endless grasping and awakening peerless insight.
This mastered to a degree, one may permit oneself to follow the flow and observe the manifestations. As Wang Pi says, "only desire that is rooted in emptiness can be in any way beneficial". In other words we have to "give rise to a mind that is unsupported anywhere" as the Diamond Sutra says - to be open-hearted, open-minded and open-fisted in order to see the "manifestations" clearly, otherwise all we see is our own version of them, which is not at all the same thing.
BOTH of these arise out of the mystery. This is similar to the idea that samsara and nirvana both manifest as the 'recognised' or 'unrecognised' manifestation of primordial buddhahood - that ultimately they are identical for all that their results are as far apart as heaven and earth. Wang Pi points out that "... at the start, mystery is referred to as 'origin', and, at the end it is called 'mother. Mystery is the dark, where, in silence, absolutely nothing exists. It is where origin and mother come from and cannot be treated as something to be named. Thus the text cannot say, 'Together they have the same origin: Mystery', but instead says, 'Together we refer to them as Mystery'... The reason it refers to them is this way is that it could not just stop and restrict their meaning to a single word. Had it done so, this word - this name - would certainly have been far from the mark..."
"Mystery upon mystery" - even the known is not really known, what to say of the unknown? "The gateway of all subtleties"...
This is where the text is asking us to start: In the very heart of the unknowable and inexpressible. The rest follows on from there.
Sorry - declamatory mode. Forgive.