The present imperative in the main clause, preceded by μή, signals a prohibition in the second or third person.
The genitive signals a degree or measure (in space, time, etc.) as a modifier.
The participle signals a moment in time as a satellite.
The dative signals a beneficiary or malefactive as a complement with adjectives.
The aorist subjunctive, preceded by μή, signals a prohibition, as the negation of an aorist imperative.
This prohibition is usually in the second person, very rarely in the third. For the third person μή with the aorist imperative is more common.
In (direct or indirect) interrogative sentences the subjunctive signals that the speaker (who is always the subject) is in doubt as to whether or not he should carry out the action.
The optative with ἄν signals a possible modality in the main clause, i.e. that the speaker presents the conditions under which the state of affairs may occur as possible.
The optative with ἄν signals a modest opinion, i.e. that the speaker is certain of the reality of the action, but presents himself as uncertain. This type of optative may also be ironic.
The optative, often preceded by εἴθε or εἰ γάρ (poetic εἰ, αἰ or ὡς), signals a plausible wish.