I don't think I'd rock the boat with my modern knowledge really, but just chill and be as normal as possible, enjoying life. The one exception would be cleanliness so as to avoid plagues and other things that I'd think of having modern knowledge of germ theory.
To give you an example of what you might contend with, in terms that idea clashing with the those of the public:
"It happened again, some time after, that the same village and church were burned down the second time, and even then the fire could not touch that post; and when in (the) most miraculous manner the fire broke through, the very (unreadable word) in it where-with it was fixed to the building, and destroyed the church, yet it could do no hurt to the said post. The church being therefore built there the third time, they did not, as before, place that post on the outside as a support, but within, as a memorial of the miracle; and the people coming in were wont to kneel there, and implore the Divine mercy. And it is manifest that since then many have been healed in that same place, as also that chips being cut off from that post, and put into water, have healed many from their distempers." (1)
(1)
Bede. Bede’s Ecclesiastical History of the English People. Edited by Ernest Rhys, London: J. M. Dent & Sons Ltd.; New York: E. P. Dutton & Co., 1910, pp. 129–30.
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Many of these old texts sorely require modern translations , but here is something I got for you from Bede. Basically it's saying that there was a building post unaffected by fire, and upon the third construction of the burned building, it was implanted within the building as a relic. A healing relic; a wood post that apparently had anti-viral and anti-bacterial effects (?)
Now the thing is, that every few pages of Bede's english history has something like that running through it. Since this kind of thinking was highly popular, where touching wet splinters of wood, or garments, or springs etc. etc. could convey literal healing, then I am not sure how you are you going to convince the population of germ theory. The population seems to believe in metaphysics instead
And I'm not sure if that would help sustain the faith levels of the times, or how that might conflict with the church's interest in that particular time. For as we might see in this passage, the healing miracle / magic and the faith the church seem connected, and I don't see how that would make room for the efficacy of outside medical knowledge, in that particular context
