A point for all radio beginners to remember is that the system is VERY complicated. You can't learn it all at once, and most people are only familiar with the parts of it they use regularly.
There are NINE different radio regimes (at least!) each one involving different requests, replies, or authorisations. I doubt whether most people can even name them all, and only a radio instructor could claim to be comfortable with them all.
Just to start you off, there are THREE different regimes, depending on the type of air traffic service available at an airfield. Anyone like to list all the others?