I appreciate your approach. Mine is a little different. I don't enslave anyone I might need later (NPCs in quests, followers, etc.). I don't enslave anyone in a location (dungeon, mine, fort, etc.) that I might have to return to. The exception to this are the forts that are controlled by bandits or rogue wizards since, when the fort is cleared, they are replaced with Imperials or Stormcloaks anyway. I don't mind having the occasional Thalmor, Vigilant, Thief, etc. (from Wilderness Encounters) show up naked so I don't hesitate to enslave them. My favorites though are from those locations where you have little or no chance of returning. My earliest slaves, for instance, tend to come from Dustman's Cairn (Companions Quest) since there is virtually no chance that I'll ever return there (i never have so far). I can usually get three female slaves from there easy early in the game. Another popular spot for me is Illinalta's Deep (College of Winterhold Quest). Again, no chance that I'll go back and I can usually get a few more female slaves.