The Function and use of the Subjunctive.
Look for an η or ω where there would normally be a ο or ου or ε or ει
ὦ ᾖς ᾖ ὦμεν ᾖτε ὦσι
ONE Exhortations requests appeals with First Person Present Aorist.
Μηδ̓ ἀποκρίνωμαι οὖν Xenophon and am I not therefore to respond
TWO Negative Commands or Prohibitions
Second or Third person Aorist Only Use negative μή μὴ ἐκδῶτέ με
THREE In a final clause after ὅπως ὡς ἵνα that in order that so that
FOUR Conditional Whenever statements with ἐάν or ἐπειδαν
ἐπειδαν διαπράξωμαι ἃ δέομαι ἥξω When(ever) I (shall) have accomplished what I needed to I will come (back).
SIX After Verbs expressing fear with μή Δεδιὼς μή λαβών με δίκην ἐπιθᾖ
Or this rare example of a Perfect subjunctive from Demosthenes 19.3
Δέδοικα μή τινα λήθην ὑμῖν πεποιήκῃ I fear that some forgetfulness by you may have caused …
I probably left out a couple
Go to Goodwin's Greek Grammar which has about 30 plus pages but I suggest you do this after finiding and reading more prose samples so you will not overwhelmed by that amount of detail?