For native English speakers, attempting to learn Japanese can seem to be a very daunting task, and it is, but definitely an achievable one, and probably in a much shorter time than you might imagine.
These are a few of the tips I have used and encountered in my own slow attempt in piecing together a usable Japanese ability. I hope you find them helpful.
Focusing on listening is the fastest way to gain a foothold in the language. This is probably the simplest and most passive way of studying yet it creates a great deal of confidence and the basis for a more in depth approach. For someone living in Japan there are ample opportunities to hear native speakers in daily conversation, but for those studying outside Japan there are plenty of ways to improve your listening skills. Of course there are numerous study programs with audio materials, but I find almost all of them narrate and explain the Japanese with English. This is obviously necessary in the beginning; however, listening to Japanese only audio will allow you to begin thinking of Japanese in Japanese.
The English translations can be very distracting and I often found myself tuning out on the Japanese portion ultimately defeating the purpose of listening. With an all-Japanese audio even if my mind generally begins to wander and tune out, I am still able to pick out the few words and phrases I know, thus reinforcing their place in my memory. Another downfall of learning through translation is that the vocabulary is often tied to a single translation while the various nuances of usage associated with the Japanese word become more difficult to grasp later. Whereas, with an all-Japanese audio, a familiar word may be used in a different context and so that aspect of its meaning will naturally be included in your understanding of it.
An even more effective way to practice listening skills is by combining audio and video, such as with movies, news programs is generally the most effective way to practice my listening and comprehension. Japanese news programs are very concise and organized and, therefore, easy to distinguish when the topic changes making it much simpler to follow. Moreover, the pronunciation is very clear so that the words and their meaning are more apparent to the non-native listener.
Reading and Writing
While listening is perhaps the least labor-intensive aspect of study, reading and writing may be the most. Considering there are three entirely different systems used in written Japanese, a great deal of study is involved in mastering Japanese literacy. Beginning with kana is the most appropriate way to go; however, attempting all three systems as early as possible will hurry the process of internalizing the way Japanese is written and read.
A chart showing all of the kana (hiragana and katakana, along with a Romanized pronunciation) for easy quick reference while learning these two basic scripts is essential. Copying each character numerous times each will quickly save them to memory while enforcing knowledge of how they are written.
There are various kanji cards available to purchase; however, again writing them yourself greatly increases you chances of remembering them. I was given this advice from a friend who had mastered the language in less than six years. Making your own kanji cards aids in many ways to your understanding of the characters themselves as well as the many kanji compounds in which these characters are included. In your best hand, using the correct stroke order, write the characters on the front of the card. On the back write the various readings of the kanji, its meanings in English (though again, skipping this step and sticking with hiragana and katakana will serve you much better in the future,) and as many kanji compounds as you are comfortable with, leaving space to add more later.
Speaking practice often proves the most difficult when learning a language, but overcoming the fear to speak or the fear of making a mistake while speaking will greatly increase the chances of holding conversations in Japanese. Finding a patient and helpful listener is not always easy, especially for those studying outside Japan. This is probably the most effective way to begin speaking, however, so it may prove worthwhile to pay a minimal fee for a conversation teacher, either online or in person. However, in the absence of a conversation partner, simply repeating words and phrases from the audio materials while alone will greatly increase your ability to form the words readily and acquire the pronunciation and flow of the language. If you do happen to live in Japan, I have found the quickest way to begin speaking is to make friends who cannot speak English. This forces you to speak Japanese and though you will make plenty of mistakes and most likely be confused by a good deal of the conversation, it will greatly increase your listening and speaking ability.
The most important thing to remember in learning any new language is to keep going and though you may stumble through the process eventually you will get there.