hola greg, se puede usar el subjuntivo en los proximos situaciones
INFLUENCIA / INFLUENCE: After verbs expressing want, desire, hope, request, insistence, command, suggestion, etc., what is in the clause is like a command and must be in the subjunctive:
Espero que vayas. (I expect you to go).
B. EMOCIÓN / EMOTION: When the main verb expresses any subjective attitudes (sorrow, surprise, anger, indifference, concern, hope), the verb in the noun clause must be in the subjunctive:
Me gusta que vayas (I like the fact that you're going).
C. DUDA O NEGACIÓN / DOUBT or DENIAL: When the main verb expresses doubt, disbelief or denial, the verb in the noun clause should be in the subjunctive: Dudo que vaya (I doubt that I'm going).
D. OJALÁ (an Arabic term used to express wish or hope) is always followed by the subjunctive.