I'm thinking about infantry or even Pog units. Was what we consider hazing now more prevalent back then? Did they have weekly liberty breifs and formations on what not to do? Did they have their version of death by PowerPoint? How did leave work? What was bootcamp like? How was the culture inside the military? These are all questions I'll like answered and interest me.
You asked for information concerning "before the world wars". I assume that you are looking for information in the Turn of the Century era. The extent of the questions you are asking could easily demand a book, not a short response. Fortunately, such a book has been written, covering the era 1865-1898 (i.e. Civil War to Spanish-American War). In general terms, the life of the enlisted soldier during the latter part of this period was very much like that of the soldier before the buildup to WWI, so this book may help answer your question. I strongly recommend: Jack D. Foner, "The United States Soldier Between Two Wars" (Army Life and Reforms), published by Humanities Press, New York, 1970.
It would help if you specified what nation you are asking about, as I am sure this was widely variable.