The simple negative in Greek is ου (before consonants)/ουχ (before vowels with rough breathings) if used with assertions, and μη if used with commands, conditions and wishes. The negative normally precedes the word to which it applies.
The negative with the infinitive is normally μη.
Note also these phrases which use the negative:
ουχ ‛οτι … αλλα και – not only … but also
μονον ου – almost
ου μην αλλα – nevertheless