When you already know how to match nonverbal characteristics of your interlocutor and build rapport, it's time to focus your attention on the verbal elements.
Notice the voice pitch, tone and pace of the person that you talk to.
Check witch of those elements will be the easiest to match because matching all of them can be very hard and is not necessary.
It's hard to change the tone of voice, the pitch is the easiest but it will be best if you modify the pace of your talking.
Maybe your interlocutor interfere with some characteristic words. Notice them and use them. Of course carefully, so it won't be interpreted as mockery (it should remain unnoticed if the good nonverbal contact is present).
And first of all - the most important thing:
Distinguish what is the main rep system of your interlocutor. In that particular context does sight, hearing, or sensations dominate?
From which system you can catch the most number of words?
Do everything to translate your word into that system.
It can be a bit hard at first because we tend to be very harmonised with our main rep systems and talking in a different one can literally look like learning a foreign language.
But when you master that and start matching their rep systems, they will feel like meeting a fellow citizen in a foreign country.
Is it simple? At the beginning not so start exercising.