No different than hacking effort-wise.
The catch is that some amount of rote learning is a must. Immersion, real life practice etc is all cool, but it's just not the most efficient way. The never dying argument that children learn languages fast because of total immersion is some kind of a joke. They don't learn fast, it takes them a lot of time. The only thing they pick up fast is the accent and what I would call language intuition. But building up huge vocabulary takes them a lot of time.
So you if you want to be on the fast track you have to combine rote learning and immersion. Rote learning for cramming in TONS of vocabulary, you can do 50-100 a day with flashcards. Immersion for getting the feel.
If you're smart enough you can pretty much skip speaking practice, I know, very controversial. But if you feel like you can, then yes you can. I strongly believe it can even make things worse for some people. Because they develop bad habits too early. And I'm talking real life practice here. DO talk to yourself in that given language. Think in it. Even speak it aloud to yourself. But don't find language partners for speaking.
If you really feel like you want to do the language exchange thing then you can do it very early on, say the first month of learning. And only do text based. It's a good introduction to very basic written language. It quickly gets too easy, so you need to be aware when it stops being a learning tool and starts being 100% fun. If you can, just stay away.
Rote learning will be the hard work part of the equation, so I say try to do as much rote stuff done as you can and when you feel you're burning out just switch to stuff that's more in the immersion department. Then go back and repeat. With that method extra time that you put in actually increases the rate at which you learn exponentially. If you do 1 hour a day I'd bet that even in 6 years you'll have a long way to go. Do 6 a day and you can get fluent with an accent that is close to native accent in a year. Of course mileage varies.
Classes are totally not an option. They are full of COMPLETE slackers, language learners really do not have a good reputation, especially at an early stage (who does?).
1 on 1 tutoring is good, but don't let the tutor set the pace. The tutor is not for you to practice speaking/listening with. Of course you'll do that with him, because ideally you'll be only speaking in the target language. But his main role is to prepare your daily fix of material to cram and give you an answer when you need it. (less frequently makes little sense, bi daily at most).
I often find that it takes TONS of time to actually come up with what I'm going to cram in. Especially once you go deeper. So you can outsource that to the tutor. And do communicate that you want to go FAST (if you do :-)).
Ok. I guess it's enough, I just love learning languages. Most people think my approach is crazy, but well it works for me and I'm sure it worked in past for many many others.
If anybody wants some more crazy tips from me just post here or my email is in the profile.