The initial idioms of the letter N

not the half of it	not the only fish in the sea
not think much of	think twice
not think twice about	till hell freezes over
not to be sneezed at	not to mention
not to put too fine a point on it	not to say
not to speak of	not to touch a drop
not to worry	none too
not too bad	not too shabby
seen worse	not touch (someone or something) with a barge pole
not touch with a ten-foot pole	not trouble head about
not up to	not up to par
not up to scratch and not up to snuff	not up to the mark
seen better	not let catch doing
not all is cracked up to be	not all it is cracked up to be
not with it	not worth a brass farthing