Not sure of the meaning of "Quisiera"
I thought Quisiera meant "I wanted" (past subjunctive), but my book defined it as "Would like..." I'm confused!
I also learned that you would use 'quisiera' when ordering from a restaurant, just to give another way to use it.
"Quisiera" is the past subjunctive, used in very polite commands or requests.
It essentially is the same as "Quiera", but instead of saying "I want" you are saying something much softer and more polite.
In order of "politeness":
Quiero (informal request - I want..." you would use with someone you address as "tú)
Quiera (polite request "I want.." but more polite and deferential. Use with someone you address as "usted". Awkward, not really very commonly used. More likely posed as a question - "¿Quira darme el azúcar? Do you want to pass me the sugar?)
Querría (conditional tense - even more polite. Literally "I would want", but more accurately translated as "I would like")
Quisiera (Past subjunctive - The most polite. No really literal translation exists that you would use in English. The most "literal" translation would probably be "If it were possible, I would have wanted". But it more accurately translates as "If you could, I would like" or "if you could be so kind, I would like")
Quería (imperfect - "I wanted". Not sure where this fits in. Probably after "Quiera" and before "Querría".
Quisiera/Debiera/Pudiera en lugar de Querría/debería/podría
Querer means to want. But quisiera is querer in the subjunctive mood. It means I/ he/ she would like.
It is used when asking for something. For example "wouldn't you like to take their coats?" It's a polite way of telling someone to do something.