Have the sheep up and ready to be shorn. Have someone there to help. This may include catching sheep, sacking wool, sweeping the floor, running errands, etc. DO NOT trim feet, worm sheep, etc. at shearing time unless agreed to in advance by the shearer. This is very time consuming and is rude to the shearer.
Most shearers are there to shear and like to get on with the job.
Ask in advance. Such as, your sheep get wet and cannot be shorn. If you use dogs to fill pens and move sheep, try to keep them out of sight of the actual sheep being shorn. They can cause that sheep to fight and kick more than usual. Your shearer may be too polite to say anything, but they will notbe pleased.