I find that the main "art" of calling is not so much when the dances get going but also learning how to direct people properly in the practice. A common problem is not having men and women without some people having to pretend to be the other side (which they are not always comfortable with) so I use Tall people and Small People. Getting a circle to line up anticlockwise you can get them all in a circle first and then say man holds out his right hand, lady hold out her left and join the two hands together, To get a square get 4 couples in a circle first and then get the square from there, Be aware that small children are often included by adults in a dance but if it is a dance that requires changing partners they won't do that so make the adult/child one person and ask them to get another partner, small girls don't like dancing with small boys!, small children often have 2 friends they want to dance with not one so you have to be flexible.

There are lots of other tricks and you only learn them and develop your own style by watching others. Go to ceilidhs and take notes rather than dance - see how the caller does it. Remember during the dance itself to call slightly ahead of the action you want them to take ie start saying it about 2 bars prior.

On the band front make sure you do a clear 4 bar or 8 bar intro or two chords and play steadily. Watch the dance and don't change tunes in the wrong place as this can confuse the dancers.

Hope thats helpful

Sarah