Catholic Candle note: The article below is slightly adapted from a 2008 letter written by a vigilant father to his adult children. In 2008, he attended the Masses of the SSPX but left in 2015 because of its liberalism.
This man (the author) has always been Traditional Catholic and has been continually fighting liberalism since before Vatican II. He wrote these rules for his own children and has approved the slight adaption of this letter for publication.
In the article below, bracketed words are added for clarity, the parenthetical words are in the original.

Let me start by saying you all have been doing a wonderful job raising your families 100% traditional Catholic. Thank you so much. It is so satisfying for Mom and me.
But it is the future that I worry about. You see, I believe your toughest decisions lie ahead of you, i.e., as your children leave the nest, and the protected atmosphere of home schooling is no longer, the world will attack the children without mercy, and they will look to you for the “tough love” regardless of their pleas to the contrary.
I’d rather not write this letter, but I must. As your father and head of the family, it is my duty and responsibility to do all I can for you and future generations to keep the traditional Catholic Faith paramount in your lives. I don’t want to go through my personal judgment after death as someone who saw a problem and failed to do all I could to correct it.
The problem that triggered this letter, was the question of the need for conditional “re-ordaining” a priest ordained in the new rite. (For my concern about this, see Rule #1 below.) It concerns me greatly to hear followers of the SSPX using arguments defending the validity of the Novus Ordo rite of ordination which are similar to those arguments we heard 40 years ago, during parish meetings (and afterwards, from friends) trying to convince everyone to accept without question Vatican II and any “necessary” changes instituted by the pastor, bishops, and pope.
Those were the days [circa 1968] (before Michael Davies and the SSPX) that the majority of the priests and bishops were considered traditional, as we rightly consider all the priests and bishops in the Society [viz., in 2008, not in 2019]. Each parishioner had to decide for himself and his family what must be done to save his soul.
As an aside, let me say that I am much concerned [viz., in 2008] for the Society (“the fly”) when and if it reconciles with modernist Rome (“the spider”).
I know we can’t decide on our own whether the new ordination rite is certainly valid or not. The Catholic Church will officially resolve this question in the future. But in the meantime, we have to save our souls; no excuses of blind obedience will do. So, it’s time to pass on the four rules in writing that have served our family well over 40 years, keeping us 100% traditional.

Rule #1: Never, Ever Trust Anything Coming out of Modernist Rome.

Cardinal Ciappi, papal theologian to five consecutive popes, said that, in the Third Secret, the Great Apostasy in the Church begins at the top. Example: the 2007 Motu proprio. I believe the Tridentine Mass and the Novus Ordo were put on the same level to corrupt the Tridentine Mass by blending the two. I think it very possible that someday traditionalists will have to drive a good distance to find a non-blended Tridentine Mass. [Remember, this is 2008.] Even at the outset, [now-former] Pope Benedict XVI is already suggesting new Prefaces and Saints (St. John Paul II some day?) be put into the Tridentine Mass. If the pope was serious about spreading the use of the Tridentine Mass, might he not start saying it himself?
Our Lady predicted this corruption in Rome as the Abomination of Desolation and diabolic disorientation. She offered the solution: Consecration of Russia to her Immaculate Heart. Until the pope and bishops of the world renounce modernism by consecrating Russia to her Immaculate Heart, you should not trust anything coming out of modernist Rome. Rome has been under attack for many centuries, but during the [Second Vatican] Council it completely surrendered.

Rule #2: Be on Guard against Compromise and Gradualism, two of the Devil's Favorite Weapons, Plus Pride.

This especially holds true for the father, who is the head of the family and bears the greatest responsibility. It is important to be vigilant for any sign of compromise, usually followed by gradualism, (regardless of strong social pressure). Like movies, TV, music, women’s dress, and attending the indult Mass, etc. As you all know, give an “inch” in these areas and children will take a “mile,” and feel justified.
Once the compromise is established, it’s very difficult to revert back to where you started and ought to be. The next generation will then take note and take the matter further “south.” Yes, we have some responsibility for the salvation of our grandchildren’s grandchildren and will be judged accordingly. Never get on the slippery slope of go-along-to-get-along.

Rule #3: Pray, Pray and Pray some more, especially the Family Rosary Morning and Night.

I know you all do that, but I thought it best to repeat it.

Rule #4: You can’t afford to give Blind Obedience to our Priests and Bishops, even from the SSPX [prophetically written in 2008].

They are only human. In these times when the world and the Church are upside down, we must remember the costly lessons learned over the last 40 years of deterioration in the human element of the Church. Many started good and gradually went bad.
Remember, a bad tree cannot bear good fruit. And you’re either with Him or against Him.

Conclusion

The above guidelines are not new and were not intended to be. But there is value in writing them down for reference now and in the future, to be passed on to the next generation at the appropriate time.