find in amasone "living language Ultimate japanese" and if u will get interested in it - take the one with CD's - at least i am very satisfied by it (used as primay studying sorce, and now as secondary - took a language lessons).
the other good thing to have is "flash card manager" (if i spelled it correctly). this is usible if u sit at the PC for longer times. u can use a lathin ABC (normal) and, if u have, japanese - pretty good one
the roseta stone is not THAT good as it sounds. u see a picture of a boy kneeling and holding some stuff and u really dont have an idea what they have in mind
for roseta stone u will need to get some basic grammar.
thats my opinion and its only subjective. i have found one lesson guide, that can be used for making self studying plans and ways of learning stuff, but i lost a link long ago