1. There is some debate but stand five car lengths away from a parked car (some say four car lengths but I am sure I read somewhere they suggested five car lengths)
2. Open Google Maps and right click and select Measure Distance. Find somewhere where cars come to a stop (at a junction or traffic lights) and measure 20m from this point. Zoom in and have a reasonable idea where to stand to be 20m away - some locations will not be safe but it shouldn't take long to find somewhere where you can stand on the pavement and be 20m away from a never ending stream of random standing cars.
3. Not sure on this one but I believe the car should be stopped and there should be good visibility.
4. If you are doing a measurement obviously make sure you test cars that are coming toward you otherwise it is cheating
![Wink ;)](./images/smilies/icon_e_wink.gif)
5. When you go for an eye test they should be able to tell you whether you meet the minimum requirements for driving with / without glasses.