Here is the Megalithic Portal Listing for Cnoc An Aird Standing Stone:
There is actually a couple more Sites on the Isle of Arran. You can find them using the Megalithic Portal Search Engine. The Sites that Megalithic Portal needs Pictures of are listed being colored Green. Sites that they have Member Pictures are listed (such as what Aska posted) as being Red.
As far as Etiquette, when did my 2006 Tour of England, I burned Incense on the North, South, East and West Corners of the Sites that I visited. That was Corrin’s Tower in Isle of Man and a Circle of Sarcen Stone in the Treasury Room on the Old Sarum Cathedral Ruins. So in my Opinion, Burning Incense is Perfectly Acceptable way to pay Respects to such Ancient Sacred Sites.