Why should we save our spookiness just for October? It's always more startling to see something when you don't expect it. However, I'm not encouraging you to be that neighbor. These things take subtlety. After all, seeing a witch on your front lawn in March is just disappointing.
In my yard I have a sea of ferns along the side of the house. I'm thinking I could put the silhouette of a skeleton rising out of them. You wouldn't see it till you rounded the corner, really. That would probably be unexpected. The shape of a man or a group of wolves at the edge of the woods near our fire pit would be spooky too, I think.
Chartini's Yard Art has some great pieces. Bookmark this shop for Halloween. Order now and you'll be sure to have what you need when October rolls around. Just remember, a little goes a long way.
There are hundreds of holiday cut outs available. Each is made as they're ordered so remember to order early.