How may languages should one learn?
I am from the USA and i'm learning spanish as a second language. I'm loving spanish so much that I must now ask the question, "how many questions should one learn?"
12 Answers
I would say you should learn as many as possible! It's best to start with the ones you are most likely to need in your life (when you travel) and with the most common languages (such as the UN languages)... You never know where tomorrow will take you, so it doesn't hurt to be prepared for anything! 
I think that question can't have the answer. Some people are languages bums, others can barely speak their native tongue, it'd be pretty much up to you to decide how many, I, for example, would like to command two other languages, or at least as good, or bad, whatever, as my English is today.
I would agree with lydianish1 that, if you are so inclined, learn as many as you can! I really love the Romance languages, particularly Spanish (of course), and Italian. But someday I would love to be able to speak fluently, for example, Mandarin Chinese, since it is the most widely spoken language in the world, and also German, French, etc. Portuguese would also be really cool to know. But knowing Spanish gives you a head start on all of the other Romance languages, so it's a great place to start. I also think that diagonx is right; this question is very subjective, that is, there is only one answer that is right for you but what's best for you, might not be best for me, or lydianish1, or diagonx, or anyone else. So it's ultimately up to you to decide. ¡Buena Suerte! Good luck!
I have to admit that languages are really not my strongest suit. Having been a miserable failure at both Spanish and German in school, it has been a great experience to feel some sucess in Spanish now that I have studied it on my own. For me, I doubt if there are any more words I can cram into this tired old brain, but for someone who has the determination I can't think of a more rewarding mental persuit than learning a new language!
Good question, good answers, I agree w/them all. I think it's best to try to master your native tongue and one other language, unless you're really gifted at learning languages or grow up in a place where they speak multiple languages. "Jack of all trades, master of none" theory... That being said, it's also cool to see how different languages are inter-related and have common roots and influences. I guess it also depends on your goals and what you want to do w/the language skills, e.g. travel, teach, conduct business, talk to friends/relatives. Some people love languages and learning them, some have a knack for it, others don't, some are curious and want to be challenged. Also, once you learn one 2nd language, I think it's easier to learn more. Most importantly, enjoy the journey!
As many as you wish, learning a language does not hurt, but I'm sure that you will need a language other than your native's in the future. Especially if you have related people abroad so that you can communicate with them and if you are planning in studying/working abroad, this will make things easier. And if you love travelling like I do, try to learn the language of the country you're visiting, it'll be ALOT easier to go around, and you'll have more fun :D 
Aprender un idioma no materno es muy complicado... You can take 10 years and not be able to communicate fluently.
Has de ser constante y dedicar muchas horas... Yo aprendo inglés, y me hubiera gustado ser nativo inglés para poder ser capaz de hablar en este idioma sin errores...
At least I'm a native Spanish and like we say "algo es algo" (it's better than nothing).
I believe one should learn one second language, and learn it right. The key word is learn. That language "should" possibly be the one that is most needed where you are (outside your native language). Then your third+ language can be whatever you'd like to learn. You could try to learn learn as many languages as you'd like. It's not really a "should" type of deal.
I studied latin for three years in school, I have studied Hebrew and now Spanish. I want to get this perfected because I am sure I will be using it in the very near future.
Learning another language opens up the world in many ways. Learning a second language makes learning a third easier, especially if it is in the same language family. I have studied Spanish, German, and French. For me, Spanish has been the easiest and German the most difficult.
As many as your heart desires....
I am on my fifth language.
It's always good to become fluent in a language before you tackle a completely different language... If you sort of learn spanish and then start french it's like saying I sort of know spanish and I sort of know french, better to say I'm fluent in spanish
