Take the airport bus to its terminus, or come out of the station to Waverley Bridge
Walk south towards the Old Town
Cross the road and go up Cockburn Street
Continue (unless you want to take the shortcut up the steps on the right)
Turn left at the end of Cockburn Street
Round the church
Along South Bridge to the first road on the right
Along Chambers Street
Past the Museum
Turn left at the end of Chambers Street
Left onto Bristo Place
Along Bristo Place to the end
And you're there!