follow this all the way to Edinburgh, taking the lane for ‘City Centre’ at the Hermiston Gait roundabout at the Edinburgh end of the M8.
You will have to be carefull when you get to this point. If it is rush hours, roughly 4pm-6pm, then the route from the airport right into the centre can be very busy and very slow. If it is not directly in the centre you are staying, another option is to take the city bypass (ring road) and come off at one of the junctions that has a good link to the centre i.e. ‘Gilmerton’. This way is faster than the ‘direct’ route at these times, providing you are not staying right in the centre of Edin.
Also, as mentioned, you can also get the bus. There is the main airport-centre bus, the ‘100’, which is pretty regular and benefits from the use of the faster bus lanes.