Missum imperatori de pestilentia is one such guideline, written in 1371 for the emperor Charles IV for dissemination.
It was based on the Paris Plague Concilium Tractate of 1348 written by the faculty of medicine members for king Philip VI of France.
In contrast to what is emphasized on that wiki-page, it not only contained some 'scientific' explanations, but also guidelines for the healthy.
Since this founded a European tradition of thought for such occurrences, its basic recommendations are found in countless later Regimina sanitatis or Regimen pestilentiae.
One such pest-regiment is on WP as

A page from the "Pestregiment" (1482) by Hans Folz. Source: Renate Smollich, "Der Bisamapfel in Kunst und Wissenschaft". Deutscher Apotheker Verlag, Stuttgart 1983.
(LLC: This page mainly a didactic poem on the proper ingredients for a Bisamapfel/Pomander, a ~'scent-apple', used for it nice smells and the preventative and curative powers the ingrediente confer. Depending on the ingredients used, this was more than just 'aroma-therapy'.)
More of the details resembling modern 'guideline' or the most beloved by all non-'pharmaceutical as well grossly unscientific interventions' (NPI) can be read in summary
Don't get the contagion, avoid infected, avoid getting poisoned, by:
- get fresh and healthy air (including 'clean your air with pleasant smokes')
- painstakingly avoid places where the sick are
- use prophylactic medicines (herbs, to clean your insides)
- eat and drink healthy, that is: in moderation
— Ein Kurtzer vnd nützlicher bericht wess sich die gesunden / vnd
krancken in der ferlichen zeytt der pestilentz vorhalten sollen.
Durch Johansen Sigismunden Goerlitzer / der Ertzney. Doctorem ordinirt vnd gestellet. Anno M. D. Liij.
A direct descendent of the Paris tractate would also be found in
— Karl Sudhoff: "Ein deutsches Pest-Regiment aus dem 14. Jahrhundert", Archiv für Geschichte der Medizin, vol 2, no 5, 1909, pp379–383. (That author was a collector of such 'regiments', a German version of Missum imperator pestilentiae is here.)
These guidelines and recommendations were copied and slowly expanded when republished as letters or short pamphlets. The Missum imperatori pestilentia adds basically these recommendations:
- get used to blood letting
- avoid plagued places and plagued people
- use smoke and fire to cleanse your sleeping room
- eat breakfast late and 'sour'
- avoid public bathes
- be happy and content
- do not talk about the black death
- take a herbal plague prophylactic (fresh rue), first thing in the morning, before leaving the bed room
Towards the end of that period the first printed medical text in German language was then of this exact genre:
— Heinrich Steinhöwel: "Büchlein der Ordnung der Pestilenz, mit Widmungsvorrede des Autors an die Bürgerschaft von Ulm", Ulm, 1473. (digitized)
Directed at the common man in that city, it consists of two parts. The first part explains what the illness is, and how to avoid and prevent it, the second part is then telling doctors and pharmacists how to treat actual illness.
Tacuinum Sanitatis aimed at a cultured lay audience, says that illnesses result from imbalance of: "sufficient food and drink in moderation, fresh air, alternations of activity and rest, alternations of sleep and wakefulness, secretions and excretions of humours, and finally
the effects of states of mind."
It was an 11th century Arabic treatise whose translation into Latin was commissioned by King Manfred of Sicily.
The Regimen [Sanitatis Salernitanum] is believed to have been written in the 12th or 13th century, although some sources estimate this to have been as early as 1050. Even though the book bears the name of the famous medieval medical school, it is not certain if it originated there. According to tradition, the poem was written for the benefit of Robert Curthose.
The — Regimen sanitatis Salerni. This boke techyng al people to gouerne them in helthe, is translated out of the Latyne tonge in to englishe by Thomas Paynell. Whiche boke is as profitable [et] as nedefull to be had and redde as any can be to obserue corporall helthe. To the ryght excellent and honorable lorde Iohū Erle of Oxforde / and hygh chamberlayne of Englande Thomas Paynell gretynge. 1311 is a 1528 English translation of a 14th century Italian (Latin) text out of the Salerno school of medicine.