There are some blanket rules that could help you. A lot of these are simple, so apologies if you know them already.
In the short term, I’d be almost writing out a behavior management plan. In certain classroom, you’ll be on the back foot as a CRT, so you’d want to be 100% sure of what you’re going to do as different behavior arises. Consistency is key. The students need to know the rules of the game before they play.
A really amazing CRT I saw started the lesson by asking questions to the class about the content they’d learned so far, and responding with positive reinforcement. It was amazing to watch. She had the class in the palm of her hand. She acted as if she knew nothing, and the students were begging to teach her about ancient China. When they got too much, she’d single out someone doing the right thing and say “Gees, it’s so good to see Jessica sitting patiently with her hand up. What did you want to say, Jessica?”. This broadcast the ‘rules of the game’ and suddenly the whole class was sitting quietly with their hands up.
You also don’t know what resources will be available when. Some teachers bring everything with them when they leave, due to people stealing their resources all the time. I’d suggest making a list of all the things you require to teach and bring a bag yourself. Massive whiteboard markers, as thick as your arm, are great. You can get them from Officeworks, and even the kids up the back can see your writing.