What helps one remain steadfast upon the Sunnah?
The first thing is asking Allah ﷻ.
Say, "O Turner of hearts and eyes, keep my heart firm on Your religion".
The Messenger ﷺ used to say this, though he was infallible.
Yet he did not feel safe from Allah ﷻ changing his state, so he would say:
"O Turner of hearts and eyes, keep my heart firm on Your religion".
Supplication is the first thing. Second: learning.
Learn beneficial knowledge by which you know truth from falsehood.
Guidance from misguidance, and wrong from right.
Learn from the people of knowledge.
And in schools of knowledge and study circles like this. Yes.