Positive approaches to behaviour management will make the life of a Cover Supervisor so much easier so work at it and reflect on what works well for you.
Build a repertoire of what is the best tactics you have tried and the impact your style is having on pupil behaviour and learning.
Some of the words above are useful in creating the culture you want when you are covering lessons,
Be clear and consistent
Reward and celebrate
Clear learning objectives
Explain with clarity
Show approval and reward effort
Model your own behaviour and be a model for your pupils
Looks like you haven't made a choice yet.