Easy for you to say! Chinese speakers have an unfair advantage, really. But it’s true that Chinese loan words make up a huge portion of Japanese vocabulary, and they do practically constitute a separate language. And that many sounds that would be distinct in Chinese are homophonic in Japanese. I find myself digging into Chinese vocabulary more and more, but I’m always aware that my pronunciation is atrocious and would probably be incomprehensible as well.
Easy for you to say! Chinese speakers have an unfair advantage, really. But it’s true that Chinese loan words make up a huge portion of Japanese vocabulary, and they do practically constitute a separate language. And that many sounds that would be distinct in Chinese are homophonic in Japanese. I find myself digging into Chinese vocabulary more and more, but I’m always aware that my pronunciation is atrocious and would probably be incomprehensible as well.
I still struggle to code-switch when I encounter onyomi readings, often pronouncing the terms incorrectly. ;)
My best methods for learning onyomi readings have been mnemonics (not the most ideal for everyone) and vocabulary.
When you know vocabulary tied to a kanji, you also know the readings (with some exceptions, like irregular readings). So when you see 今 and you know こんげつ→今月 then you know at least one onyomi reading for it is こん/コン. Likewise, you know at least one onyomi reading for 月 is げつ/ゲツ. The more vocabulary you learn with the kanji, the more readings you'll pick up. It may be much slower than mass wrote memorization of readings, but much more practical for some, and easier to remember.