>>83
Not as much as you would think. I know a few germanic languages prior and I could figure out 75-90% of the words from either the context or the similarities with words from various other languages on the first few times, then I just memorized the words.
When learning a new language. Get the alphabet down as the very first thing. Afterwards grammar and some more grammar with only the bare basics of vocabulary, so that you could form correct sentences / manipulate words. You can usually get this down in a good week or so.
Then I try to get my grammar to the intermediate-advanced speaker level and get used to it, once I do that, I'm pretty much finished. After that, get a good dictionary and a few nice novels, the first few books will read extremely slow, afterwards your speed will increase in a rapid tempo and you will only need to look at the dictionary at rare times. This is also how I learned the vocabulary that I know, learning words by hard and reciting them is a stupid and a time wasteful way of learning. While reading a book you can remember the meaning of the word either by itself, if you read the word for enough times, or get the meaning from the context of the sentence.
Afterwards, I watch shows, listen to music, radio in the specific language. To get the hang of recognizing the words spoken.
Using this method I usually get to a fluent level of understanding the language in roughly 2-3 months, for speaking, the best thing to do would be to go that country and just... well speak the language.
By doing this, I can usually get fluent in a language in a time span of roughly 1 to 7months (depending on the languages and similarities between them), naturally, the more languages you know the faster will the process be for learning new ones. If you lets say 2 slavic languages, learning the third one shouldn't take more then 2months, if your fast, you can get the hang of them in a few weeks. Especially if you know some older languages.
For Italian / Spanish, I suggest you look up some Latin. If you get the hang of Latin, you basically have the blueprint for all of the languages in Europe in your head.
Can't recommend anything for Korean or Japanese tho, I was never extremely interested in what lies in the far east.
Don't mind the typos / fucked up grammar too much, I came back from a party just recently and simply put, I'm kind of wasted.