This guide begins using kanji from the beginning to help the reader read "real" Japanese as quickly as possible. Therefore, we will go over some properties of kanji and discuss some strategies of learning it quickly and efficiently. Mastering kanji is not easy but it is by no means impossible. The biggest part of the battle is mastering the skills of learning kanji and time. In short, memorizing kanji past short-term memory must be done with a great deal of study and, most importantly, for a long time. And by this, I don't mean studying five hours a day but rather reviewing how to write a kanji once every several months until you are sure you have it down for good. This is another reason why this guide starts using kanji right away. There is no reason to dump the huge job of learning kanji at the advanced level. By studying kanji along with new vocabulary from the beginning, the immense job of learning kanji is divided into small manageable chunks and the extra time helps settle learned kanji into permanent memory. In addition, this will help you learn new vocabulary, which will often have combinations of kanji you already know. If you start learning kanji later, this benefit will be wasted or reduced.
Certain characters (especially the most common ones) can have more than one 音読み or 訓読み. For example, in the word 「怪力」, 「力」 is read here as 「りき」 and not 「りょく」. Certain compound words also have special readings that have nothing to do with the readings of the individual characters. These readings must be individually memorized. Thankfully, these readings are few and far in between.
訓読み is also used in adjectives and verbs in addition to the stand-alone characters. These words often have a string of kana (called okurigana) that come attached to the word. This is so that the reading of the Chinese character stays the same even when the word is conjugated to different forms. For example, the past form of the verb 「食べる」 is 「食べた」. Even though the verb has changed, the reading for 「食」 remain untouched. (Imagine how difficult things could get if readings for kanji changed with conjugation or even worse, if the kanji itself changed.) Okurigana also serves to distinguish between intransitive and transitive verbs (more on this later).
Another concept that is difficult to grasp at first is that the actual readings of kanji can change slightly in a compound word to make the word easier to say. The more common transformations include the / h / sounds changing to either / b / or / p / sounds or 「つ」 becoming 「っ」. Examples include: 「一本」、「徹底」、and 「格好」.
Yet another fun aspect of kanji you'll run into are words that practically mean the same thing and use the same reading but have different kanji to make just a slight difference in meaning. For example 「聞く」（きく） means to listen and so does 「聴く」（きく）. The only difference is that 「聴く」 means to pay more attention to what you're listening to. For example, listening to music almost always prefers 「聴く」 over 「聞く」. 「聞く」 can also mean 'to ask', as well as, "to hear" but 「訊く」（きく） can only mean "to ask". Yet another example is the common practice of writing 「見る」 as 「観る」 when it applies to watching a show such as a movie. Yet another interesting example is 「書く」（かく） which means "to write" while 描く （かく） means "to draw". However, when you're depicting an abstract image such as a scene in a book, the reading of the same word 「描く」 becomes 「えがく」. There's also the case where the meaning and kanji stays the same but can have multiple readings such as 「今日」 which can be either 「きょう」、「こんじつ」, or 「こんにち」. In this case, it doesn't really matter which reading you choose except that some are preferred over others in certain situations.
Finally, there is one special character 々 that is really not a character. It simply indicates that the previous character is repeated. For example, 「時時」、「様様」、「色色」、「一一」 can and usually are written as 「時々」、「様々」、「色々」、「一々」.
In addition to these "features" of kanji, you will see a whole slew of delightful perks and surprises kanji has for you as you advance in Japanese. You can decide for yourself if that statement is sarcasm or not. However, don't be scared into thinking that Japanese is incredibly hard. Most of the words in the language usually only have one kanji associated with it and a majority of kanji do not have more than two types of readings.
Some people feel that Japanese should have just switched from Chinese to romaji to do away with all the complicated characters that was bewildering the foreign white devils. In fact, Korean has adopted their own alphabet to greatly simplify their written language to great success. So why didn't it work for Japanese? And I ask this in the past tense because I believe that the government did attempt to replace kanji with romaji shortly after the second world war with little success. I think anyone who has typed at any length in Japanese can easily see why this did not work. At any one time, when you convert typed hiragana into kanji, you are presented with almost always at least two choices (two homophones) and sometimes even up to ten. (Try typing kikan). The 46 or so character alphabet of set sounds in Japanese makes it hard to avoid homophones. Compare this to the Korean alphabet which has 14 consonants and 10 vowels. Any of the consonants can be matched to any of the vowels giving 140 sounds. In addition, a third and sometimes even fourth consonant can be attached to create a single letter. This gives over 1960 sounds that can be created theoretically. (The sounds that are actually used is actually much less than that, though I don't know the exact number.)
Since you want to read at a much faster rate than you talk, you need some visual cues to instantly tell you what each word is. You can use the shape of words in English to blaze through text because most words have different shapes. Try this little exercise: Hi, enve thgouh all teh wrods aer seplled icorrenctly, can you sltil udsternand me?" Korean does this too because it has enough characters to make words with distinct and different shapes. However, because the visual cues are not distinct as kanji, spaces needed to be added to remove ambiguities. (This presents another problem of when and where to set spaces.)
With kanji, we don't have to worry about spaces and much of the problem of homophones is mostly resolved. Without kanji, even if spaces were to be added, the ambiguities and lack of visual cues would make Japanese text much more difficult to read.