Not losing
Seriously, I am not kidding. You just never fight a fight you do not win. Before you commit to a fight you evaluate the odds and if they do not look very good, you do something else. Do this and you will never lose.
Doing this has some requirements.
Intelligence
In both meanings of the word. You must avoid being taken by surprise or estimating the odds wrong. Cavalry is good at scouting and your people have training and education to understand what they see so this should be possible.
The issue is that the cavalry that is good at scouting is light not heavy but it would make sense to have permanently attached light cavalry scouts and screen. They could be trainees or junior knights.
Mobility
The enemy must not be able to force a bad fight on you. This is generally not an issue with cavalry operating independently but there are some points you need to remember.
You must be free to move. You need to operate independently from rest of the army. You must not have defensive responsibilities that pin you down defending a position. And the enemy should not have cavalry fast and strong enough to force you to a losing fight. So you'll want some reason why the enemy cannot field strong cavalry or why it is not able to force an engagement on its terms.
Remember that your logistics need to be able to keep up! So you either have a very fast pack train or only operate in areas where you do not need to carry much supply.
Short engagements
You must not be engaged in combat long enough for enemy to pile in more forces. This is actually good for shock cavalry. You see a vulnerable point, you smash it with a charge and disengage to a safe distance and start looking for another opportunity.
Freedom to leave
If a battle starts going badly you must be able to leave. Preferably with a valid and honorable reason that does not hurt the reputation. So do not participate in battles without secure retreat. And always have valid reason why somebody else should delay the enemy.
Being the fastest part of the army with best ability to get away is a start but unfortunately it also makes you good unit to buy time for slower units so more is needed.
I am thinking some sort of holy relic that the force is sworn to protect. They carry it with them everywhere because they are sworn to always protect it personally, this includes to battle. And if battle turns out badly, they just have to keep it safe from the enemy by carrying it away as fast as possible. And of course they all need to go as well since they are sworn to protect it. They just cannot stay behind. Too bad, so sad.
Additionally a sacred relic would be very good for building up reputation. You cannot really send bards around to advertise how awesome your unit is but spreading stories of your sacred relic and its awesome God given power to guarantee victory in combat... That is just normal right? More like, it is your duty to spread word of the glory and power of God as seen as miracles of relics of his servants.