I gave a very generalized awnser to your question because I didn't know your situation. Why someone wants to learn is very important when it comes to learning a langague, especially Japanese. There is no method that fits all.

If it is important for you to start speaking right away, it's probably a good idea to learn grammar first and leave writing and reading for a little while. Other than that, you should start learning kanji. Among beginners, there is this belief which floats around that kanji is this giagantic, expert-level task which should be left till last when you are at a have a strong grasp on everything else. This is false and ineffecient, this is essentially bottle-capping how much you can learn. If you don't know kanji, you can't read and anything you write is difficult to read. Whenever you learn new kanji, you learn a handful of new words; if you don't learn the kanji for the compund words you learn, synonyms will get confusing and it leaves just more for you to learn later.

Yes, I will stick to my hiragana and katakana to start there first. I will download the app you mentioned then also find a book on writing kanji. I want to build up from a basic understanding to memorizing as much as I can. For now I'll get basic sentences so I can start having conversations. I'm leaving to Japan next month!!

What do you think of that you will start from kanji which Japanese children learn in the first grade of primary school?

http://www.mext.go.jp/a_menu/shotou/new-cs/youryou/syo/koku/001.htm

My resources are generally phone apps. Something I can do when waiting around, bored, or just to have easy access to. You know, Instead of carrying lots of books around with me all the time. Check out what type of apps are on your phone device and see what they have to offer for Japanese related programs/games. Some will teach you stroke order, some will have memory games, or flash cards/etc. A site/app I used when learning reading/writing/and speaking skills for Japanese is Memrise (http://www.memrise.com) a good writing site/app is Skritter (http://www.skritter.com/) 

As Delisha mentioned in the comment section above; "You don't need kanji to start writing Japanese sentences." You also don't need it to speak, obviously because hiragna and katakana tought you the vowels/pronunciation, from then on it is grammar structure and vocab. Kanji is still improtant nonetheless and even though you can write sentences in the kana you already know, kanji will need to become apart of it eventually. Check out this site on why Kanji is necessary. ( http://www.tofugu.com/2008/05/31/6-reasons-why-kanji-is-necessary/ ) Now what Ariana said is very accurate too. There are very many different ways to approach learning kanji. Yes, Japanese people do learn at least a minimum of about 2,000 kanji and usually by the end of junior high school but those are the basic characters. Used in like newspapers, magazines, and school text books. Most Japanese people know several thousands additional kanji as well. "There is no shortcut, once you start learning kanji, you are going to continue to be studying them years later if you aspire to be fluent."