You can probably start from any season or level you find comfortable. Ultimately doesn't really matter much.
Lean Kana from the start. They're easy and necessary. You can learn the read them in the course of an afternoon by simply googling for flashcard programs. You can also mess around with
http://www.humanjapanese.com/preview/HumanJapanese.aspx , which will tell you about how to write them, and includes sound files for pronunciation. There is no reason not to learn the kana as quickly as possible; it's easy, and you need them to read anything in Japanese that is not specifically aimed at foreigners.
Kanji will take longer. Everyone has their different ideas about it, but I personally suggest this website
http://kanji.koohii.com/ and the book it is designed to work along with. For more information, I would direct you to
http://kanji.koohii.com/learnmore.php ,
http://forum.koohii.com/viewtopic.php?id=1958 , and maybe
http://www.japanesepod101.com/forum/vie ... php?t=4075 or some other threads in here about RTK that you can find through a search. In that last link there's also a link for
http://www.nanzan-u.ac.jp/SHUBUNKEN/pub ... sample.pdf , which is a free sample of the first section of the book.
Good luck and feel free to ask for any clarification...