Kanji grouped by on-yomi reading with ascending ‘commonness’ of onyomi reading.
http://funbit.info/kanji/readings/on_table_by_grade.html
Scroll down for the commonest readings (attached screenshot)… I hope your good at visualizing Shoguns, Koichi, Sheep and Genghis Khan! …cos there are loadssss of them. Personally, I’ve changed all those mnemonic elements to ones that are vivid to me rather than struggle with WK suggestions.
I’m finding this information helpful in planning how I’m going to represent onyomi in my mind, so I thought I’d share it.
(Link shows 1945 Yojo Kanji in total, pre-2010 set)