When do I have to use the subjuntive?

The subjuntive is used to express desire, doubt, emotions, probability and the unknown.
It is usually used after these common expressions:Quizás (doubt), puede que (posibility), me gustaría que (desire), ojalá (desire)Keep an eye on them when reading texts and you will find the subjuntive is more commonly used than you thought!
Top tip: do it wrong. When you are unsure of something or you have a desire: mix the present tense endings! (-ar verbs now have in -er endings; -er verbs have -ar ending and -ir verbs have also -ar ending now)