Use visual aids as the children come in - it is calming, distracting and reinforces the message that assemblies are a different learning environment. Candles, props, posters and PowerPoint pictures can be helpful.
Your choice of music needs thought. It is safer and calmer to use classical pieces rather than the current number one - this can lead to spontaneous clapping or singing, which is not the environment you want and it's harder to focus the pupils afterwards. Leave the exciting pop until your confidence grows.
If you struggle with some of the older children, get them involved, holding props, doing drama, helping with younger volunteers. It keeps them in line and keeps the others interested too. With younger children, use puppets and always make assemblies as active as possible.
When using stories try for intrigue and interest; stop new stories before the ending and discuss potential endings, especially if the story has a moral dilemma. With a familiar story have a repeating line that they can all chorus.
Add a bit of the "sparkle factor" and it is easier to keep their attention. The story of Jesus turning water into wine can be improved upon by using clear jugs of water and a tiny bit of food colouring.
Kate Aspin is a senior lecturer in education at the University of Huddersfield.