Hello there.
Just wanna share my experience and hope it helps. The way of memorizing those things is "feel it" and "express it". I have been learning Japanese on my own since last year and I came to this fabulous forum.
As you may see there is a pretty good chatting-in-Japanese thread in this section and there're a few really nice and sweet Japanese people helping us out. Try writing something in Japanese and post it, I am sure there's always someone who can spare his/her time helping you out. (for eg, the great handsome fabulous N_y_ san! oh and K_G_ too!) Or, you can look for a Japanese email-pal here (or in other section?) where you can force yourself writing some Japanese.
It's not hard to learn how to read, but it's always a challenge to write it properly. The only way is write it and learn from the correction.
Good luck!