A roll of fishing string and some creative thinking , you can have people shaking in their boots. You just need the "tour guide" to be able to know exactly where the strings are. Any type of noise to get people looking away from where the string is so they dont see you puling it. Just make sure to test and double test.
Example- box of leaves, or feathers, or something similiar up in a tree. Arrange box so that when you pull the string, it opens and the contents drop.
If there is a shed you will be going past, string one of those little hand garden rakes on a string next to the wall. Run the string over the door . Puling the string makes scratchy sounds on the wall. If the door is slightly open, and you have a flashlight to shine in there , a good shining of the flashlight, scream and slam the door shut and lock it.( the idea behind this is to show there is NOT a human in there )
Once, with practice, I had a scary looking doll sitting against a tree. Its head looked attached, but wasn't. I ran a string from one tree downhill to behind the dolls head. There was a little fake hatchet attached in a manner that it would slide down the string quite rapidly. With the pull of one string, the hatchet seemed to come flying from the darkness. when it hit the dolls head, I pulled the other string, making the dolls head fly off. You could put some sort of waterballoon thing filled with reddish goo there so when the hatchet hit, it splattered the red stuff like blood.
A slight indention in the ground, with a "ghost" inside covered with leaves, and a string pull can make the ghost rise out of the ground. Gravestone optional LOL
A black sheet or one of those cheap dollar store plastic black tablecloths Strung between 2 trees can have any type of horror scene behind it. A pull of a string can lower the sheet, making the scene behind it suddenly visible.
Stuffed animals,and rubber rats are cool to use also. Attched to string, they can be pulled across the path.
Oh, I used to LOVE doing the haunted house thing.