4. If you usually keep your iPhone in your pocket make sure that the surface finish of the case has low "drag." Trying to extract an iPhone in a "sticky" case while sitting down becomes a feat of strength and will involve contortions that are unwise when driving or enjoying air travel.

5. Beware of fancy painted or textured finishes, they will wear off and or get dull.

6. Make sure that the case doesn't prevent you from using the iPhone with any brackets and holders you might use in your car, boat, hovercraft, Chieftain tank, etc.

7. If you decide you really like a case and have just got to use it but you might have to take your iPhone out occasionally, check that the case can be reasonably removed and that it won't get damaged after a few goes of putting it on and taking it off. I've had a couple of cases crack after two or three removals.

8. If the case covers the "hold" button (that's the button on the top surface on the right as you're facing the screen) and or the volume buttons, make sure that the material over the buttons isn't so stiff that the buttons are hard to press.