If I am familiar with a person, but either don't know where they are or aren't familiar enough with their location to teleport there, is there any method of teleporting to the person rather than his or her location?
The easiest way would be to scry on your target. Simple cast a scrying spell, and you can see the area immediately around the subject. Since you can see the area, it counts as "studied carefully" for the purposes of Teleport, which makes it pretty easy to get there. Since you're familiar with them, they get a -5 to the will save, assuming they don't want you to see them.