Chances are that after several years of watching anime, and/or reading manga you have gotten to the point that you can easily understand a few Japanese slang words and phrases as you most likely hear them repeatedly in the medium. Words like "Ohayou Gozaimasu" and "Ja ne" and "Moshi Moshi" and even "Doku desu ka" are some fine examples of everyday language that one will pick up on when watching their anime subbed, and listening with the Japanese audio enabled.
Learning a new language is a great achievement, and one that takes a lot of hard work, and much practice. This isn't at all like riding a bicycle, because if you DON'T use it, you will LOSE it.
Learning to speak Japanese is one thing, but learning to read Japanese is a totally different monster. Much like English has Upper Case letter and Lower Case letters Japanese has something almost similar, but used often-times in a different contrast.
Then to complicate matters further, there are the ported Chinese Kanji that are whole words represented by a symbol or symbols. To further complicate the language there are these particles that are used to string the words into a sentence that define the flow of the conversation into something more than just base words and subjects.
It's easy in the American fandom for fans to get a sense of what sounds right and what isn't right when they've listened to a language enough, but the real trick is in the translation.
Many fans assume that there is only one literal translation for a word, and this couldn't be further from the truth. In the sense that we have words like "See" and "Sea" that obviously mean two totally different things but are pronounced the same.
Or take "No" and "Know" also to similar sounding words that have completely different functions.
To complicate the learning of Japanese, their alphabet does not contain some letters that are more prevalent in English, such as "L" and "Q". Because the Japanese language is a phonetic language that does not change the way a letter is pronounced it isn't difficult to learn pronunciation, an "A" will always sound the same no matter where it is placed in a word, and a "O" will always sound like an "Oh" and not a "Uu" when there are two of them placed side by side as in "Soon".
Probably the three most difficult things to learn about Japanese is:
1) The Alphabet
2) Sentence Structure
3) The various Forms of Speech (Polite, Proper, Casual)
Also it's good to remember that instead of there being multiple similar sounding words that have different meanings, there are multiple words that sound nothing alike, that have the same meaning.
Now for those of you that think you can learn to speak Japanese simply by watching imported anime, and Japanese Cinema, well you are sadly mistaken. First of all, much of the dialog in a film or TV show is going to use a more general form of the language, unless the characters are using a specific type of language, or honorific direction.
This means that there are totally different ways of speaking and addressing people given the social encounter. Much of the language in an anime is between two or more friends that toss around silly nick-names and childish honorifics, that if were used in a public forum, or Professional institution would result in much offence and probably some insults.
Another thing to remember is the "Ga" "Wa" "No" "Ka" of most sentences. These are like verbal punctuation and subject indicators. "Wa" usually indicates the topic, and "Ga" is the subject. Not to mention "Wa" and "Ga" are some of the hardest things to grasp about the Japanese language.
Where one describes something, the other specifies what or who.
I am reminded of something I mentioned yesterday about the new anime Kuroshitsuji and that the English title is Black Butler. The question was why did they use the name Black Butler for this anime and manga, and I explained, because THAT was the actual name of the series.
In its most simplest definition "Kuroshitsuji" means Kuro (Black) and Shitsuji (Butler). Now instead of running both words together, why didn't they just do the normal thing and perhaps use "Kuro wa Shitsuji' well that wouldn't make much sense, since the Black is not a Butler. Also "Shitsuji wa kuro" wouldn't work since the Butler isn't really the color black. so then it's more of an expression, that means the Butler is dark, black, sinister, severe, or other. And thus the name is devoid of subject indicator and topic marker.
Just like making sense of the English language, there is a good chance that if you do not take your study of Japanese seriously, you will fail to comprehend anything, or even worse, make yourself look like a moron in front of someone.
You cannot learn everything there is to learn about Japanese by online translation pages, or from watching anime. It is a good start, but it isn't a reliable resource. To really learn a language it takes patience, time, and dedication. Study manuals that offer multiple lessons, and don't just stop at basic greetings. It will do you no good to learn how to say hello and where is the bus station, if you can't hold a conversation. Or answer about yourself when asked what you do for a living, and where you are from, and what sort of work your family does.
There are some online tutoring places that offer people a chance to meet-up and learn from one another, but be careful as there are also a lot of places that just want to have you spinning your wheels endlessly.
A good balance of reading and speaking is the best solution to learning a new language. Because aside from finding out where the Supermarket is, what good will it do you to ask for directions, if you can read the product to buy something?
Start with learning to read and comprehend hiragana and katakana... these are the two basic alphabets of the language, and then try your hand at learning kanji.