Most guards were stationed within the house's province, where the House Guards enforced the will of the nobles. Small garrisons also existed in house embassies, and when official envoys from the sector traveled to other areas of the galaxy they were escorted by hand-picked House Guards.
The House Guard was open to both males and females, though the physical requirements demanded of a trooper or officer was very high. Only twenty percent of the human male applicants passed the tests, and only two percent of the human females. Almost all of the Herglics passed the test, while no Mrlssti ever had by the time of the Galactic Empire. Most recruits were drawn from the nobility, though many capable officers were commoners who came up through the ranks. Officers of the House Guard were highly trained and given the best resources their houses can afford.
The house patronage system ensured many incompetent men and women were admitted to the House Guards. The officer corps were adept at ferreting these people out however, and encouraging them to seek employment elsewhere through very unofficial, off the record and anonymous methods that included intense hazing and the sabotaging of careers (though never in a way that would endanger house security or the troops under their command).
There was a lot of rivalry, usually friendly, between House Guard regiments of the varying houses. Spies and partisans were commonly found in their ranks.