most kunâyomis are actually kana combinations that will never show up as onâyomi, which you might start to get a sense of over time. the only possible kana for a two-kana onâyomi to end in are ăăăăăĄă¤ă. (that page says ăă is possible butâŚ?)
thereâs also this userscript i like that gives a visual cue by rendering all onâyomis on kanji flashcards in katakana, which i find especially helpful when thereâs like, two kanji read ă in the same level but opposite reading types.