I would like some help with developing NPC defenses.

How do mages fortify their properties or estates?

I would assume they might have something act as sentry or protector, but are there any things I should consider? I don't want to make the NPCs seem sloppy or simple by avoiding heavy fortification, but I also don't want to make it an impossible gauntlet.

For example:

A gentleman's club guarded by various spirits (3) under the servitude of an adept ... but nothing else. The spirits are thematically related to different aspects of the club and...