My wife has a career in translation and the answer is.. as many as possible! But.. joking aside it really depends on where you are. We're in Hungary so my wife regularly translates from Hungarian to English and back, as well as some German stuff though that's not so common as it's mostly done internally and not contracted out. If you're in the US I guess you'd be looking at a very difficult market as the major languages have plenty of native multilingual speakers. In that case you need to look at the more obscure minority languages. If you're ba<x>sed in Asia then English, French and German are your best bets, If in Europe the Eastern European language sets are best as the French and German markets are flooded, lots of competition you see. Ideally, if you want a career in translation you need to be near native or native level in at least two languages preferably more with a background in language tuition. If you don't have that then it will be hard to get a position unless you go freelance.
Well, you know languages, you never really stop learning them so sure keep on learning and try to get as much native level practice in as you can especially with the German it's changing as quickly as English is.
If you're in Florida I can't see that there is much translation except possibly within the tourist industry there. I'm not in the States so I'm not clued in as to what is desirable. The best advice I can give you is to create and circulate some flyers or arrange to meet some of the local "tourist" type small business people to try to generate some business for yourself and see where that takes you. We started small in much the same way and now are quite successful, enough to employ another teacher/translator when it gets busy at least.
Good luck to you, hope you can make it work :)
English, Chinese, Spanish
I would go for Chinese.
yes very, but worth the effort I reckon. Another language I like to hear is Arabic, such throaty sounds.