I've been attempting to learn Japanese off and on for a couple years, now. I think I've restarted the process about three times. At the moment, I'm further along than I've ever been before. I have about a 90% retention rate with both hiragana and katakana. I'm back at the beginning with kanji, but I think my strategy is better this time.
Up until this time, I had been following the AJATT strategy. This is a very good strategy for some people. Unfortunately, it didn't work out very well for me. This time, I'm going with the JALUP strategy.
Step 1 is to learn the kana using a space repetition system, such as Anki. This spaces out the digital equivalent of flash cards so that you see the ones you're having trouble with more than the ones that you find easier. It's also a great tool for learn general or subject-specific vocabulary, state/country capitals, and other facts and concepts. More importantly, you can add color, graphics, and audio to each card.
Steps 2 and 3 are combined. Two is to create a new SRS "deck" for the kanji. This creates the basis for your reading skills. Three is to create cards, typically on the same deck as the kanji, that has Japanese phrases/sentences with both Japanese and English. These are the vocabulary pulled out of textbooks. JALAP recommends Genki I, Genki II, and An Intermediate Approach to Intermediate Japanese. This gives you the next set of building blocks, as it builds reading, speaking, and listening skills simultaneously. The key is to add audio for all of these cards.
Step 4 is to create a new SRS deck that contains only Japanese sentences. JALUP sells decks that contain starter sentences for those who completed steps 2 and 3 in two sets: JALUP 1000 and JALUP 2000. This gives you 3000 sentences to start with and shows JALUP's branching strategy.It's at this point where you're supposed to start trying to read easier Japanese novels, such as translated works. You should also add new kanji to your kanji deck.
So far, I have or plan to follow through with this strategy. In fact, I plan to continue to follow it beyond these, but this is where I get far more specific to what I want to get into. I'll continue on with step 4 by going to the Japanese pages of Wikipedia on subjects that I like, such as cognitive science, robotics, and space history/exploration. Once I've mined these as best as I can, I'll buy text books from Japanese on these same topics. At this point, I should be at about 8000 to 10000 sentences in my Japanese-only deck. I should also be beyond the conversational level.
I don't know how long I'll take to get to this point, but it should be a fun.