The woods were silent. Suddenly, a howl broke the silence that sounded more human than animal.
I was alone in the attic. Then I felt someone whisper my name in a voice I didn't recognize.
Sure. The doorbell rang at midnight. When I opened the door, there was no one there but a cold wind blew through me.
Keep it simple. For example, 'She walked into the dark forest. A growl came from the shadows.'
A lonely lighthouse stood on the cliff. A keeper heard knocking on the door in a storm. When he opened it, a faceless figure was there.
I walked into the forest. The trees whispered my darkest secrets.
Sure. 'The old house was silent. Then I heard a child's laughter from the attic.'
I woke in the night to a cold hand on my face. When I turned on the light, there was no one.
The old house was silent. Then I heard a child's laughter from an empty room and no one was there.
Just think of a normal situation and then add a spooky twist. For example, start with 'I was taking a bath.' Then add 'Suddenly, the water turned ice cold and a face appeared on the surface.'
They are effective because they are concise. They get straight to the point of scaring you.
The mirror showed my reflection, but when I blinked, it was someone else's face looking back at me.