Many kanji seem to have the same onyomi. For example こう is very popular, and I always go for that if I can’t think of the reading.
Do any of you have any statistics for the frequencies of onyomi?
On that note, I know that some radicals often lend their onyomi to the kanji, and even started to spot one or two (I think). Is there any resource that gives reading hints attached to certain radicals?