A dictionary of Confusable Phrases: More Than 10,000 Idioms and Collocations

know on which side one’s bread is buttered •
know which way the wind blows
know on which side one’s bread is buttered —know where one’s
interest lies: The judges know on which side their bread was
buttered. They would strain a point in favor of the highest po -
litical opinion of the day. Cf.: butter one’s bread on both sides —
be in very comfortable circumstances; be well provided for: He’s
got marble floors in there, crystal figurines on the shelves….
Like we say at home, he butters his bread on both sides.
Note:
The expression is not antonymous in meaning to the
phrase not know which end is up— be utterly confused: I didn’t
know which end was up when I first entered the classroom
and I had every problem one could imagine…
know which way the wind blows —understand what is hap-
pening in changing circumstances: I will say this for the Phar-
maceutical Association, they know which way the wind blows,
recognizing an opportunity when they see one.
know one’s way about • not know where to turn
know one’s way about—(also: know one’s way around) 
1
. know
how to get from place to place in a neighborhood: John was
a very skilled climber; he knew his way about the mountains
of Scotland. 2. be extremely knowledgeable or experienced:
She could do no better than to put her trust in a man of sub-
stance, in the prime of life, who knew his way about.
not know where to turn —(also: not know which way to turn)
be uncertain about what to do next: It became apparent that
many families of victims did not know where to turn to receive
the aid they needed.
Note:
The expression does not correlate in meaning with the
phrase not know where to look—(also: not know which way to
look) be quite embarrassed: I did not know where to look, feel-
ing embarrassed at being so openly praised in front of my col-
leagues.