A military group without formal training makes for one that is easily defeated due to inconsistent skill levels among personnel. Knowing what weapons, steeds, machines, and knowledge they require helps determine what training they receive. Some basic ability to make minor repairs might be needed, especially in SF. Are they expected to know certain languages, and does that include reading and writing them? What about understanding some neighboring settlements or sovereign powers, whether allies or enemies? The latter points are almost a given for officers, but the lowest ranks can be captured and find themselves trying to escape enemy territory. We might also decide that they’re expected to know or utilize whatever is handy and be generally resourceful.
Officers receive advanced training, typically, being college or something similar. We don’t need to specify details but can assume it includes superior knowledge of language, societies, customs, tactics, politics, and anything else that helps them run an organization better.
We should keep all training simple unless showing a character going through the details of becoming a member. But we may want to decide how long training lasts in months or years. Base this on their expected skill level but don’t get too specific unless you’ve researched what’s likely. We might say someone can become an expert swordsman in six months when an educated audience member knows better.
Decide where training takes place. There may be cities or universities that do much of it before people are deployed. This will impact the culture of a settlement due to the number of recruits there.