The Eucharist alone is our source of holiness. Only from it will you find the grace to become a saint.
The tip is simply this: Each day, strive to have absolutely no idea how many people were at Mass. (note: this is just a tip that will work for some and is impractical or inapplicable to others for miscellaneous reasons. No worries!)
How is this achieved?
By arriving early for prayerful preparation, sitting towards the front of the Church, keeping your eyes on the sanctuary – the Altar, the Tabernacle, the crucifix especially -, keeping your head down during Communion time, and remaining in prayer after Mass for a fervent thanksgiving. Do all this and you will not even be able to answer somebody who says to you “so how many people were at Mass today?”
Arriving Early: At Medjugorje, Our Lady laments that if we had any idea what a grace Holy Mass truly was, we would always prepare for at least an hour. Angels tremble before what you are about to witness – it really is worth ten minutes to ready your soul for.
Sitting Towards the Front: This is obviously the main point that will not apply to many of you, and that is fine! But if you can, I would advise sitting near the front. The unfortunate fact is that many today have no desire to be reverent at Mass, and it is better to not have such people in our line of sight, which will distract us, or worse, tempt us to pass judgments on them.
Keeping Your Eyes on the Sanctuary: Of the thousands of Masses I have attended, I can think of only a few in which something has happened that has demanded action from me. I say this because it is extremely unlikely that there is any reason whatsoever for you to look at the noise that just came from the side or the back of the Church. Nor do you need to know who walked in late, nor do you need (except in extremely rare cases) to whisper something to your spouse or your friend with whom you are attending Mass. There is no better analogy for an aspiring saint than that of a soldier; we are indeed the Church Militant. Therefore let your focus be that of warrior.
Keeping your head down during Communion time: How much it must pain Our Lord when we use those few precious moments where His substantial presence remains in us (or those few moments leading up to that heavenly embrace) to entertain vain ponderings about other people at Mass; that is more lamentable than a newlywed couple watching television on their wedding night.
Remaining in prayer after Mass for a fervent thanksgiving: Our Lord’s substantial (yes, that truly means physical) presence remains in us for approximately 15 minutes after receiving the Host – this is a simple theological/biological conclusion. It makes no sense to pray at all if we are not going to take full advantage of those 15 minutes, unparalleled in their power to sanctify. To desire sanctity but make a habit of leaving Church shortly after receiving and immediately concerning yourself with worldly affairs while He resides in you may not be an intrinsic evil, but it is at least incredibly foolish. It is like a student who wants an A, but sleeps through his examinations, hoping to increase his grade by meticulously completing his homework assignments later.
This is just one tip: the bottom line in the appropriation of the graces poured out upon you at Holy Mass is that you must be reverent, fervent, and focused – enraptured in so far as that is within the power of your will (wherein alone all merit lies) to accomplish. If ever a complaint about anything whatsoever – the world, other Catholics, your life – enters your mind as you are assisting at Mass, remember the words of Pope St. Pius X, where he attributed all the evil in the world to lukewarm Catholics; and there is no better way to be counted among this sorry group of souls than by neglecting to respond to the awesomeness of the Mass – nor is there any better way to be counted among the saints than by your faith, hope, love, and holy fear at Mass, and the wrapping of your entire being around the Eucharistic Lord you receive at it, that He alone may be the “source and summit” of your life.