Dear Gaijin Girl,
I really really want to learn Japanese. How do I do that?
My advice is don't. However, if you really really want to learn Japanese nothing I say can stop you, you poor and unfortunate soul.
With that in mind, I highly recommend you watch Japanese dramas. They are the perfect guide to speaking Japanese like real people. (Forget that anime stuff unless you want to sound like you are perpetually ready to either burst into tears or attack pocket monsters.)
You also want to watch live action dramas so you can understand the grammatical value of Japanese facial expressions and what they mean. In order to speak Japanese like a native it's important to learn the fine art of being expressionless. When you master this, you will then able to not react to anything that you perceive as negative or unfavorable. As we all know, in Japan, if you ignore something you don't like, it will eventually go away like the homeless man masturbating in the station, the foreigner trying to get the station manager to stop the masturbating homeless man or the wife at home. It's a handy skill to have when dealing with the police and the NHK man. (And you will deal with them more than you ever wanted to)
Japanese dramas are hour long shows that run for three months and then they are over. If the dramas are popular, they may have a second or third season the following year but that is pretty unlikely.
Japanese dramas are always called dramas, even if they are comedies because if the network were to label a show a comedy they would also find the need to fuck it up with story stopping gags. I'll admit to watching and loving two Japanese comics take turns hitting each other as hard as they can in the shins with metal park swings for half an hour but I wouldn't watch an hour of it every week for a season. It is unfortunate that most Japanese comics on TV have very little or no control over their material or their career and make very little money doing it. If you ever wonder why the contestants on Japanese gameshows are never civilians but are always comedians trying to win things like cheese and ham, it's because they are broke and hungry. They are literally working for food.
Japanese dramas also let you in on some important and commonly held beliefs in Japan. The first being that if you are caught in the rain without an umbrella, you will get sick and probably die. A strange pair of shoes in your genkan or entrance means your significant other is cheating on you. A half eaten boxed lunch means a husband no longer or never did love his wife. Anybody with a necktie around their head is a drunk asshole over 50. Any drama with Kimura Takuya or Kimutaku in it is good. (Though the theme music will be bad.) Any drama where the lead is a female is antifeminist propaganda. Japanese people who speak English too well are evil. (American movies are also guilty of this. In them, the devil is always a white guy ridiculously good at speaking Russian or Chinese.) Marriage proposals are never romantic and if you fall in love with the wrong person (or your ordained by the gods soul mate) you will also fall into a coma or go blind.
Enjoy and good luck,