I don't know much about languages but I'm a firm believer in the full immersion from the start variant. ( I suppose relative ignorance is a prerequisite for firm belief... )
I went to DR with no Spanish, but as soon as I landed on the
airport I started handing out my mom's homemade cookies and
kicked it off from there. Luckily, Spanish is quite easy compared
to the other languages I've experienced. The pronounciation and
grammar ( particularly the verbs ) is far easier to deal with than
say French, English and the Scandinavian languages ( Norwegian
in particular, though there the verbs are are easy. It is the nouns that make no sense ). The Spanish grammar is a neat,
flourishing garden, French grammar is a jungle.
Reading, listening and talking to everyone with no fear of making
a fool of oneself is also a basic requirement, methinks. Within
two months I was trying to explain basic English and Spanish
grammar to 50 rather unruly Dominican pupils as their regular
teacher was absent. Newspapers, academic texts, Petit Nicholas translated from French and of all, Gabriel Garcia Marques was what I started with. ( The latter is unreadable in any language, that's why he got the Nobel prize. )
I'm also very aware when I talk to people, always picking their
sentences apart and copying whatever is said and how it is
being said. Then I try it out on another innocent victim. I left
Ireland with a pretty good Irish accent, but now I spend too
much time with people from Sri Lanka so I sound like a Tamil.
I prefer private tutors rather than big classes. What I want
in my first lesson is a complete picture of what I need to know.
I.e. the complete grammatical structure of the language, including all the verbs in all the tenses. I want to be able to say:
"I want this and that", the vocabulary will come along later. As
a student I can be quite a pain for a teacher, but I'm paying so..
My brother achieved fluency after 6 months, Argentinian accent.
I can't match that, but from my level now I'll be ok in 6 as well.
Colombian accent.