She will also share her knowledge in a two hour music theatre workshop Saturday at Wauchope & Port Macquarie Performing Arts.

Eisteddfod coordinator Angela Johnson said there are still places available for the workshop which starts at 10am and costs $30.

Harrison will discuss audition and warm-up techniques, conduct theatre games, talk about musical theatre and guide a master class performance.

The multi-talented performer is known for her roles as Betty in Sunset Boulevard, Ellen in Miss Saigon, Liza in The Boy from Oz, Ellie in Leader of the Pack, Paula in the world premiere of An Officer and a Gentleman, and Oz in We Will Rock You, for which she was awarded the 2004 Helpmann Award for best supporting actress in a musical.

Her advice to nervous competitors is to concentrate on breathing and practice.

"The more you do it, the better you get at it, but preparation is the key," she said.

"Know your lyrics back to front so even when you freeze a little, your brain will spill them out for you."

The versatile star said she will be looking for a connection to the character and an understanding of the lyrics from competitors.

"I listen for tone and look at overall energy of the performance, that x factor.

"Kids have in-built confidence but they have to be able to back it up."

Friday at Port Macquarie Uniting Church classical vocal, aggregate and junior vocal championships start from 1.30pm and open classical and community choirs from 6.30pm..

Saturday the contemporary vocalists, championships and aggregate sections start at 1.30pm with open sections starting at 6.30pm.

On Sunday from 10am the over 50s and music theatre sections will be adjudicated with another session at 1.30pm and the music theatre groups and open solos from 6.30pm.

To reserve a place at the Amanda Harrison workshop go to www.cmnc.org.au and click on the box office button.