One aspect which should be developed during the MCC/JOC/APS is “line flying R/T”, appropriate from the first exercise.
Up to this first multi crew course, you have probably used a modified style which I refer to as “training R/T”.
It was necessary to ensure that ATC were aware of your intentions. Now you are operating as an airline crew, you need to move away from this style without delay.
There is a considerable amount non standard / slang phrases used which sounds awful. Absolute Garbage.
“Roger that” : “weather copied” to name but two.
There is a thread on the ATC forum : Annoying habits
This is worth a close read. Now just be warned that all ATCOs have their own views on what is good & bad.
The definitive answer for UK aviators is CAP413.
You will find that the more discerning MCC Providers have produced one page of A4 setting out exactly what phrases are appropriate based on CAP413.
Note: In these days of Political Correctness, and for the avoidance of doubt, the phrase “junior birdmen” is a generic phrase not identifying any particular gender.