To write a good villanelle, you need two strong lines with the same rhyme and meter. Those are your A lines that become the refrains. Another line goes between them, and that sets your second rhyme, the b line. It can have a different rhythm, if you want to create tension or variety; or use the same rhythm as the A lines for tighter cohesion. I like this form for its balance between repetition and variation. It's a good match for weighty topics, for things that make you circle around the same idea or two competing ideas.
So here's a look at some villanelles I have posted online:
"Fiorenza and the Sea" (Fiorenza the Wisewoman"
"This Curséd Gift"
"The Treasures of Marco Polo" (The Silk Road Allies)
"What Evil Must Be Done"