I've heard that quisiera can be used to mean "I would like ..."
When the subordinate clause in the sentence must take the subjunctive, like in the lyrics:
Yo quisiera que vivieras/
De mí siempre enamorada
Quisiera que sepas que lloro en silencio
(from Christian Daniel), should we follow up with the subjunctive imperfect like Reik does, or with the subjunctive present like Christian Daniel? Or are both correct, with different meanings?