Social combat.
Also, the stunt 'honest lies' is a good one for that.
I think it's not so much that they don't lie, it's that they don't always tell the whole truth.
Player: "Do you really mean that?"
Fairy: "Don't you know that fairies can't lie?
Notice that the fairy didn't actually admit to being (dis)honest. (S)he just stated a fact and let the players connect the dots.
A player might say. "You didn't answer the question. I want a yes or no answer!"
I think it's best to do it as straight deception rolls or social combat if you, yourself, are not naturally adept at manipulating the truth. And if the character failed to catch the deception, then it should probably be RP'd as such. Deception is a tricky beast in this game, I find. The mechanics are designed to be played out on the table, so the players usually know when they're being lied to. As long as they don't play their characters that way.