Well... you see, I have a very different problem than most Japanese learners.
I know all the kanas. I read Chinese, and so I don't have a problem recognizing and writing kanji. But I don't know the
kun reading of the kanji, and sometimes when a phrase contains both kanji and kana I get confused.
I know the word order, and if you throw me a bunch of words along with properly-conjugated verbs and particles, I know how to put them together properly into a sentence (including relative clauses, subordinate clauses, etc).
I know *some* verb endings (but not enough!), and what I really need help with is recognizing parts a verb. The Japanese writing system is partly to blame for this. For example, consider the following forms of "to read":
読む "yomu"
読みます "yomimasu"
読んだ "yonda"
読まない "yomanai"
読もう "yomou"
読め "yome"
If you look at the romaji, it's clear that the root meaning "read" is "yom-" (the "m" turns into an "n" in "yonda" due to phonological reasons). So it's easy to separate out the root from the suffixes. We can say that "-imasu" is the formal present form, "-ta/da" is the past tense suffix like "-ed", "-e" is the imperative, etc. But looking at the kanji/kana combinations, it's much harder to draw the line. 読 itself isn't the root; it can't even be pronounced on its own. And also, while with the romaji we can say that "if it ends with just -u it's the dictionary form", we can't do that in the kana cases. For example:
話す (hanasu)
書く (kaku)
待つ (matsu)
Although they all end with "u" and are conjugated the same way, the kana at the end of the dictionary forms is different for each word. Instead of just recognizing a "u", you have to remember that く, す, つ, ぬ, ふ, む, and る should be treated the same way. Of course, if you're saying the words out loud, it's fairly obvious that they all rhyme. But it's not so obvious when you're not reading out loud. And reading out loud is hard when I don't know how the kanji is pronounced.
So yeah, manga is great because in many cases the hirigana is given next to the kanji. But it's also got drawbacks in my case, because manga tends to contain less kanji than a regular novel or newspaper, since it's geared towards a younger audience. And I rely on the kanji to figure out where a word starts, because when you see a kanji you can be almost certain that it's the beginning of a word. Consider:
八時に起きて学校に行った。
I can read this and break it down as:
八時に---起きて---学校に---行った。
Each of these parts start with a kanji, and seeing this, I can understand the parts: "at 8:00---waking up---to school---went". But if the sentence was written completely in hirigana (which no one would do, since these are simple kanji, but you know what I mean...):
はちじにおきてがっこうにいった
Now I have no clues to work with, and can't cut up the sentence.

You don't write spaces between words like you do in English; it'd be so much more helpful if they'd write it as:
はちじに おきて がっこうに いった
So yeah, I'm pretty much backwards from everyone else learning Japanese, and so regular textbooks and things don't help me very much.