Rewrite your riddle. Tighten it up. Put it aside. Come back, then tighten it up some more.
This is your quality control. QC can be brutal but worth it. Send the riddle to a few of your friends. Make sure it can be solved. Request feedback on how well it's written, how easy it was to solve, and any other thoughts they might have about the riddle.
Don't send the riddles to your sugary sweet friends who might want to spare your feelings. Send it to the sarcastic. Send it to the filterless. You want honest answers, not feeling-sparing praise.
Then rewrite some more. Send it back out to new friends. Request more feedback.
Rinse and repeat until your riddle is ready for prime time. You are almost ready to turn it loose on your students... or even use it in an escape room game