My current textbook of choice
That last method is the I one I must be the most careful about. It's not the whole casual versus formal dilemma. I'm not too worried about sounding casual--as a foreigner, I figure I'll be given a bit of leeway. As long as I don't cuss out someone, informal speech is much more useful since it's spoken everyday. And when needed, if I try to mix in -masu form and desu enough, it'll show that I want to speak formally but don't really know how.
What I worry about is that at school everyday, I'm surrounded by female colleagues. After school, my Japanese tutor is female as well. Most of the Japanese I hear everyday comes from women.
Therein lies the problem.
In Japanese, men and women sound different. This makes sense if you consider there is different vocabulary for the different sexes. Gender roles are clearly defined in Japanese society. This distinction carries over into speech. This means that if a woman uses really strong words that only a man should use, she is thought to be lesbian (or at least, very masculine). So if the reverse is true as well...
This whole time, I've been talking like a girl.
Don't get me wrong--I don't use blatantly feminine words like 'あたし' for I, or 'わ' at the end of a sentence. I don't giggle like a school girl nor does my voice sound like I'm whining. However, when I speak, I don't sound very... strong. So a phrase that may sound OK in my head, a normal Japanese man would never say. One example is adding 'よ 'to the end of every sentence. In a textbook, it's described as a strong male ending... but in the real world, men use it a lot less than women.
For example, when someone used to ask me '本当か,' my instinct was to reply, 'そうよ.' I recently started thinking about that phrase (and why my tutor laughed at me when I said it). I've never heard a man say that expression, whether in anime, TV, or real life. I wondered why it sounded so natural... and then I realized that at school, the teachers surrounding me say it all the time. If you listen to men speak, though, they would respond with 'そう.'
Another very basic thing I say all the time is 'ね.' I may respond to someone's statement with 'ちょっとね.' Normally, it's when it's something bad and I want to agree but not fully sound negative, so I just reply "a little bit, huh?" "Oh today's very cold." "Mmhmm... ちょっとね." In English, there's no real difference saying, "A little bit," versus, "A little bit, huh?" However, in Japan, men don't use 'ね' as frequently. It's much more feminine in Japanese to soften what you say all the time. Another instance: Women say 'そうね.' Men say 'そうだね.' Guess which one I've been using this whole time...
Note that this only applies for my everyday speech. When I drink, this problem disappears. My Japanese becomes a lot more masculine, albeit vulgar, as a night progresses (though the same is true of my English, or any other language for that matter). I don't necessarily want to use my drunk Japanese as my normal speech, but it'd be nice find a mix between the two. I'll just have to keep on trying to find that balance.
No, that sounds too weak. I ought to use something stronger. Otherwise, it's no better than when I speak in Japanese.