Because of Yuki (Dangerous)'s ability to spread traps quickly coupled with a solid statline, traps such as Flamethrower and Present Thief can be spread easily to hurt characters that need cards to compensate for lesser stats.
Due to her statline, Gift Exchange can be used to great effect to disrupt card play with little harm to herself.
Yuki (Dangerous)'s hyper allows her to draw traps quicker, making it more likely powerful traps such as For the Future of the Toy Store is drawn. She can also place the aforementioned trap at over 50 stars with her hyper.
Try to place traps in threatening areas. While landing one on someone's Home is often best, 1-6 spaces after a Home also tend to see a lot of traffic. Avoid placing them on a fork and attempt to get them on convergent points.
Pay attention to the number of cards in the deck before using your hyper. If there are only a few cards left, it's possible there are no traps and your hyper will miss; wait for a fresh deck before using it.