General Golf question 1 about Greens?

How do you READ a green? What are you looking at? What are you looking for?
I’m going to be a tad more specific. Although all the answer are great, here’s the crux of the situation. Can you really tell which way a green goes by "eyeballing" it with your putter? Maybe i’m just not getting and its been a while since i’ve truly "whacked the ball".

try plumb bobbing

hold your putter in front of you with 2 fingers on the top of the grip

line up the bottom blade with the ball

with your non-dominant eye closed start at the ball and slide up the shaft till you see the hole

your putt will break towards the side of the grip the hole is on