Thumb and Finger Independence for Fingerstyle Guitarists

I got a question from a blog reader recently that said:
How, in your mind, can you coordinate both a bass line with your thumb and a melody line with your fingers? I can’t seem to divide my mind that way. What can I do to gain finger independence?
There is a 2 part answer!

The Physical Answer
Off the bat, you need to have a few “basics” in place with hand position. You probably know this, but it’s always good to re-visit basics.

Your thumb must be OUT past the fingers
Your thumb should NOT hide behind the fingers
Your thumb should move from the big