New to taking insurance

Early career, private practice. Up until now, I have been private pay only. Starting fairly soon I will be paneled with a couple of different insurance companies. Diving into that murky pool.

If any existing clients want to switch to using their insurance, are there specific things that would be helpful to talk with them about? The utility/necessity of diagnosis and medical necessity, for instance. Curious if others have navigated this shift and have helpful tips to share. Thanks!