The title page of the 1835 Doctrine and Covenants reads:

DOCTRINE AND COVENANTS
of
the church of the
LATTER DAY SAINTS:
CAREFULLY SELECTED
FROM THE REVELATIONS OF GOD,
and compiled by
JOSEPH SMITH Junior.
OLIVER COWDERY,
SIDNEY RIGDON,
FREDERICK G. WILLIAMS,
-[Presiding Elders of said Church.]

It is also important to understand what the purpose of the record is, which is stated clearly in the Preface:

To the members of the church of the Latter Day Saints—
Dear Brethren:
We deem it to be unnecessary to entertain you with a lengthy preface to the following volume, but merely to say, that it contains in short, the leading items of the religion which we have professed to believe.

The first part of the book will be found to contain a series of Lectures as delivered before a Theological class in this place, and in consequence of their embracing the important doctrine of salvation, we have arranged them into the following work.

The second part contains items or principles for the regulation of the church, as taken from the revelations which have been given since its organization, as well as from former ones.

There may be an aversion in the minds of some against receiving any thing purporting to be articles of religious faith, in consequence of there being so many now extant; but if men believe a system, and profess that it was given by inspiration, certainly, the more intelligibly they can present it, the better. It does not make a principle untrue to print it, neither does it make it true not to print it.

The church viewing this subject to be of importance, appointed, through their servants and delegates the High Council, your servants to select and compile this work. Several reasons might be adduced in favor of this move of the Council, but we only add a few words. They knew that the church was evil spoken of in many places—its faith and belief misrepresented, and the way of truth thus subverted. By some it was represented as disbelieving the bible, by others as being an enemy to all good order and uprightness, and by others as being injurious to the peace of all governments civil and political.

We have, therefore, endeavored to present, though in few words, our belief, and when we say this, humbly trust, the faith and principles of this society as a body.

We do not present this little volume with any other expectation than that we are to be called to answer to every principle advanced, in that day when the secrets of all hearts will be revealed, and the reward of every man's labor be given him.

With sentiments of esteem and sincere respect, we subscribe ourselves your brethren in the bonds of the gospel of our Lord Jesus Christ.
JOSEPH SMITH jr.
OLIVER COWDERY.
SIDNEY RIGDON.
F[rederick] G. WILLIAMS.
Kirtland, Ohio, February 17, 1835.

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Knowing these things, it seems to me that we should very much cling to what is recorded in that book. However, I know that it is very much changed from what Joseph provided from the Lord. Therefore, I often make use of this pivotal Wikipedia page - https://en.wikipedia.org/wiki/Doctrine_and_Covenants  On the left side of that page (as seen on a computer) there are bookmarks of the content. One of those is a chart, comparing the different versions:
https://en.wikipedia.org/wiki/Doctrine_and_Covenants#Chart_comparison_of_editions.  

Please note that there is a column for the 1835 edition, and the 1844 edition, with a description of the contents in the far right column.  The 1844 edition was hurriedly published the month following Joseph and Hyrum's murder, which was July 1844.  There are significant changes in that edition, to chart a new order of things.  So, each of these should be studied carefully to discern the purpose, and research the original documents.  One thing that was changed is Tithing.  It was made mandatory, and 10%. Also, Baptism for the Dead had two new sections added.  Prior to that time, the Temple focus was to prepare the Saints to meet God, while in this life. This is a quick list of Sections that should be researched in order to discern, with God's inspiration, which is from Him, and which is not.
Sections Not in 1835 or 1844:    2, 13, 77, 85, 87, 108 -111, 113-118, 120-123, 125-126, 129-132, 136-138                         

Sections Not in 1835, but included in 1844: 103, 105, 108 -111, 112,  119, 124, 127-128, 135

We have only discussed the additions to this sacred record. But, there are two significant passages that were removed in the 1876 and 1921 editions. In 1876, the Church removed the Statement on Marriage, which indicated that the Law of God is for one man to have only one wife. That was in both the 1835 and 1844 edition. In 1876, that was removed, and the current section 132 was the replacement, which introduced the doctrine of polygamy.

In 1921, the Lectures on Faith, which was the Doctrine portion of the record, was removed.