That is LOADS of work

It's something I've been working on more or less every day for a few hours. I've read a lot of books, including: the art of speedreading people, Tricks of the mind, 3 books on speaking which I can't remember the names from, the absolute book of body language, Influence, and some more plus a lot of articles on nlp, I have a 1 hour a week training from a family member of mine who is a psychiatrist.
And the most important part, I've been practicing a lot. First on people I know, and starting this week I've been just Talking to anything trying to read stuff, and attuning myself to it.
As for guessing if I had enough rapport to bounce, that was a big guess

But basically you look for IoIs, I normally just look for a slight tilt in the head, playing with hair and I've been trying to get to notice pupils getting bigger, but I find that hard.
I wouldn't recommend doing this

Only if your really interested in it.