Teleportation is a mightily fun superpower. What I have problems with is how many times this is abused for no reason at all. As an example, the Nightstalker (I think) in X-men can teleport short distances, but will one moment do a backflip just before teleporting and as he re-appears from his teleport he is suddenly not doing a somersault, has turned around, facing an opponent that was outside of his vision, and is halfway through a punch with enough energy behind it to knock an opponent unconscious. Basically, when exiting the teleport the character is in position with whatever energy it wants. It even allows them to teleport into/out of moving vehicles without problems.
To get a better idea what a realistic teleporting person would go through, I have the following assumptions:
the person can teleport anywhere in their line of sight.
accuracy of the teleport is based on how well they can see and aim for the target area.
the person teleporting will inherit their bodily position, energy, and movement he had at the point of teleporting.
all material the person is carrying is teleported with him. No molecular bonds are broken this way. So, clothes are teleported along but if you carry your friends arm it wont be ripped off - simply not teleported with you (unless you bodily carry your friend).
the teleporter will swap with a volume of his size, swapping only with gasses or liquids but no solids totalling more than 200kg/m^3 (337 lb/yd^3) (the point is that you can still replace solids dispersed in air and water, not to make this a hard limit. Change the value to something that works if and when necessary). If the teleporter makes an error (say, placing his feet into the ground) he's teleported at maximum 1m (1.1yd) away from his chosen destination where no solids prevent his teleportation. If that is impossible, no teleportation happens.
Now imagine someone who decides to follow the highway towards his destination. He teleports a distance he feels safe with, so he doesn't accidentally end up on the highway. Each time he teleports he would logically need to regain his bearings rather than be able to teleport instantly again.
The question is how fast would an average person be able to gain his bearings and teleport again?
I originally thought this would be as simple as the average reflex time. But that only deals with reacting to one stimulus, not with appearing in an environment and choosing the next destination that is safe and in the direction you want.