Twiddling your thumbs
is an expression which means waiting around idly.  It is also a habit some people have of clasping their fingers and rotating their thumbs round each other without touching them together.

I’m all fingers and thumbs
could be said by someone finding a fiddly job difficult.

“One finger, one thumb keep moving” is the first line of an action song.  It has more parts of the body added in each verse and finally becomes quite complex.

I can’t put my finger on it…
…but I know something is not quite right.

“Tommy, Tommy, Tommy, Tommy,
“Whoops Tommy, whoops Tommy,
“Tommy, Tommy, Tommy.”

This rhyme is an action game, which tests people’s powers of observation.

To know somewhere like the back of your hand
is to know it very well.

“Look, no hands…look, no teeth!” is what a little boy on (and off) a bicycle is supposed to have said.

Wringing one’s hands is the action required to rub in hand cream.  It is usually done in sorrow.

Hand to mouth is living improvidently.

Hand over fist means rapidly and comes from the action needed to climb a rope.

Don’t let the left hand know what the right hand is doing.

This expression comes from the Bible.  In the Gospel of St Matthew Chapter 6 verses 3-4 (NIV)  Jesus said, “But when you give to the needy, do not let your left hand know what your right hand is doing , so that your giving may be in secret.  Then your Father, who sees what is done in secret, will reward you.”