Remember use the mouths of your NPCs to describe your world. Refugees will be glad to unburden on those willing to listen, so make it worth the party's time to stop and listen. Take some time to craft a bit of scripted dialogue to add flavor to your monsters. Monsters are scenery in your world so be colorful and try to build them up as the party goes. Rummors, children's stories, tales of chance meetings all add an air of aloofness and anticipation your players will enjoy.

Example:

"Her presence is often described as tangible fear. That doesn't begin to describe the way my body shutdown the first time I met her. Muscles freezing as my heart seized, pulse beats hours apart as the air evaporated in the vacuum of her majestic malevolence. My eyes stuck open as if trying to consume the entirety of her beauty in one glance. The ruby colored scales heaving with each breath, the sound of countless treasures of log forgotten kingdoms crunching between her talons. The sheer awe of her size several leagues high and disappearing in to the cavern behind. Tendrils of smoke wafting forward from her nostrils carrying the sent of recently charred flesh."
"Then a "harrumph" and a smile, if she could smile, showing an army of pointed teeth in random rows."

Remember to work these types of narratives in to a few sessions before they actually meet the monsters. Use the players' memories to build their characters' memories.