speakable conlangs

Someone who'd heard me say some K'tle words suggested I make a language that's easy to speak. The obvious thing would be to work on my auxlangs. However, I made a few notes, mostly with question marks. One idea is to use the final vowel for valence on verbs and animacy on nouns. I got the following mnemonic scheme:

-a animate noun
-i inanimate noun
-e expressed object of verb
-o omitted object of verb
-u unused

I wonder what other affixes could be made mnemonic?