This is a post from my old blog, from May 2011. It’s part of a series of resurrected older posts that I still think are useful for language learners. This particular post has been heavily edited for clarity and brevity.
Chinese ≠ Japanese
Perhaps 90% of Chinese characters are composed of both a radical and a phonetic. For Japanese learners, ignoring this phonetic component when learning characters is fine – the radical-phonetic link is not apparent until a large volume of Chinese loan-words have been encountered. Furthermore, characters are commonly loaned for native Japanese words irrespective of pronunciation. Thus, for some characters, it may take a lot of time and frustration to identify the radical-phonetic link, so Prof. Heisig’s method of using sophisticated mnemonics to remember seemingly-randomly composed characters is appropriate.
By contrast, in Chinese languages, the radical-phonetic link is more commonly encountered, especially given the higher number of characters in common usage. (Japanese is commonly quoted as having 2000-3000 commonly-used characters, whereas Taiwanese students are supposed to have learnt upwards of 6000 characters.)
Take for example characters in which “我” (“ngo5”) is the phonetic. 哦, 鵝 and 蛾 are all prononced “ngo4” in Cantonese – the meaning are “oh” (an exclamation, hence the mouth radical), goose (with a bird radical) and moth (with an insect radical). If you were following Prof. Heisig’s method, you might spend 5 minutes coming up with images for each character; however, it takes virtually no effort to remember each of these characters if you exploit the meaning-pronunciation information of each. (By the way: there are a couple of other semi-common characters too which fall within the Taiwan character list, like 娥 and 峨, both of which are also pronounced “ngo4”, so it’s basically “buy-one-get-five-free”.)
As you might expect, there exist characters that do not conform to the above rules. There are still 10% that were formed in another way (e.g. as pictograms or ideograms), and which thus need to be learnt some other way. In addition, some of the radical-phonetics have changed pronunciation over the centuries to the point of the original phonetic link no longer being clear. 義 (ji6) and 蟻 (ngai5) are ready examples in Cantonese… although the Mandarin pronunciation is still ‘yi’ for both of them.
The Quick and Easy Road
So, the shortest path to full character literacy is probably not to come up with Heisig-style mnemonics for every character. For Chinese languages, one would probably save a lot of time if one could identify the building blocks and highly irregular characters. Rather than mnemonicking how to write 6000-odd characters, we could perhaps reduce this number by up to perhaps 75%.
Our list of characters to learn mnemonically would come from a combination of Heisig’s primitive system (around 300 primitives), characters that aren’t radical-phonetic compounds and characters where the phonetic component has become extremely irregular. The rest of the characters would be dealt with using trees of relatively-regular radical-phonetic characters.
Who knows how it might turn out?
 This is an arbitrary, made-up number. I don’t know how many radical-phonetic characters have highly-irregular pronunciations.
 Please read the introduction to “Learning to Write the Kanji” – available legally online in PDF format – if you’re not sure about what ‘primitives’ are in this context.