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
(from Reik)
and
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?
The proper way is to use the subjunctive imperfect. Bear in mind the songwriters may use colloquial or incorrect expressions if the lyrics fit better in the melody. If you want to know how it is written it's better to look at books. In the Spanish Orthography by the Royal Spanish Academy you can read these two examples when speaking about the use of querría/quisiera in paragraph 23.15u:
Yo querría que este momento durara siempre.
Yo quisiera que tú la conocieras.
Yes, you can use both tenses querría and quisiera as "I would like". But if what follows is a relative clause you must then use the subjunctive imperfect. If not, you can use the infinitive:
Quisiera ser un pez para tocar mi nariz en tu pecera.
(Yes, this is from another song by Juan Luis Guerra.)
To use the subjunctive present you should change the tense of the verb querer:
Quiero que este momento dure siempre.
Quiero que la conozcas.
