For starters: Have a strong sense of plot. Know the events of your story.
After that? The fae like making deals, and they love information (and by extension, power) more than even humans. They gossip on a scale that gives them access to almost anything they want to know badly enough. Because of this, it's probably safe to assume they know the story almost as well as you do. This is a shortcut/aid in helping them plot further ahead, and risks making them seem omniscient, but with practice and a careful hand, can be done to great success.
As to speaking in riddles and not lying, remember that even more than Fae like knowing secrets, they -love- selling them. That's what makes that information powerful, the fact that others know it. They -want- the people they're talking to be wowed and enticed. Being cryptic to the point of obfuscating information or being frustrating to the players isn't the goal. As "Your Story" puts it, the Dark Powers are always willing to help. Make the first taste free, then hook them with the promise of making the cryptic comment clear.
In short, prep ahead of time. Not inherently to the point of rehearsing every line, but spend three or four hours really getting into what these creatures in specific know, and what it means to them. Maeve is going to speak cryptically in a very different way than say, Mother Summer.