HAND-WRITE LYRICS FOR MEMORIZATION
If you are iffy on the words and know deep down that they won't roll off your tongue readily, write the words down. And I mean, properly write them out old-school on a piece of paper with your fingers physically gripping a pen or pencil.
Trust me. This technique will solidify those words into your brain. Write out each verse until you get it correctly. The same goes for the chorus and bridge. And then, go back and write out the entire lyric to the song.
You're way less likely to forget words in moments of distraction or technical difficulties if you use this trick.
Don't stop, get it, get it (even after messing up).
Remember, that no matter what happens on stage, you need to keep going. You'd be surprised how your audience will go with things as long as you believe it. I once sang the wrong word in the middle of the national anthem. Though mortified of my mess up, past experience had taught me I'd better not flinch, and in fact I acted as if that was exactly how it was supposed to go.
My conviction must have worked. Afterwards an audience member complimented me on my rendition being one of the best they'd ever heard.