Quick answer
indicative (habla, tiene) = you present something as a fact.
subjunctive (hable, tenga) = the clause is wished for, doubted, denied, or still hypothetical.
The trigger sits in the first half of the sentence, before que. Learn the openings, not the feeling.
Side by side
Memory trick
Cover everything after <i>que</i> and look only at the opening. Wanting, doubting, feeling, denying or an unreal future pull the subjunctive; knowing, saying and seeing do not.
Typical mistakes
Quiero que vienes a mi casa.
Quiero que vengas a mi casa.
Querer que always takes the subjunctive, because you are asking for something that has not happened. English "I want you to come" hides this.
Cuando llegas a Madrid, escríbeme.
Cuando llegues a Madrid, escríbeme.
A one-off future event after cuando needs the subjunctive. The indicative here would mean "whenever you arrive", as a routine.
Check yourself
Fill in: "Espero que ___ bien el examen."