If you are playing Scottish Country Dance, you should really be calling the dances as well i.e. explaining the dance beforehand and then 'calling' out the moves for the first two or three times, depending on the dance. The most well known will be:
Dashing White Sergeant - Two groups of three (MFM or FMF)
Gay Gordons - Couples, in a circle, males on inside
St Bernard's Waltz - Couple, in a circle, male on inside, slower tempo so good for 'a wee breather'
Strip the Willow - Couples in sets of four or for simplicity, and more fun, Orcadian Strip the Willow.
The comment about two songs in a row is not strictly correct. If your song is 2 mins or less then doing it twice is ok, but certain dances, like the Eightsome Reel, last about 6-8 minutes so once is sufficient.
Something you can now do, if your equipment allows it, is to have a 16 bar loop at the end of the song, which you allow to play so that everyone has a turn (with set dances) or if you feel that they've had enough and are slowing down, just end the loop and finish the song.
You might find
this a useful resource, or if you'd prefer to have the music as well as instructions, try
this