I use acronyms that are easy to remember for actors, here is one of them
F.E.A.R. this is what makes a good haunted house actor.

F rightening
E nergetic
A ware
R eliable

Frightening -is pretty obvious, they are paying to be frightened while they are in your show, they want to be scared run three steps then laugh. thats when you are doing it right

Energetic - is all about pacing being able to deliver the same show at 1am that you delivered at 8pm. Energy is about being able pace your self and learning to operate on a level 7 energy level most of the night, that way when you need to you can turn up the dial, if your burn on level 9 then when you need to you do not have any more to give. Its treating your body right so you can maintain your work through the night and the season.
Awareness - This is the most important thing for a haunt actor. awareness is knowing where the groups are, and who is in them. its knowing that the gap between two people you see through your peephole is a 4 year old who is not tall enough to be seen, not a good space to jump out (thats how I kneed a 4 year old in the face). Its getting to your set before show and noting that there is a bulb out and notifying the manager so its fixed before show. Its knowing that light and sound levels were set the way they are for a reason and you should not change them without permission. Awareness in knowing that the actor behind you has an issue and needs you to stall the group and being able to do so without dropping or breaking character and in such a way that the stalled group never even notices it.

Reliable - almost self explanatory but you will never fully understand unless you are the owner and you are short four actor how important reliability is. Be ready to work (in costume and make up) 20 minutes before show opening. Reliability is being on set for every group except when you are on break, its also coming back from your break exactly on time. Its also making the most of the set you are needed in and not complaining about little things.

Im not the best typer in the world but that "pearl" is a biggie, I use it alot and the actors repeat it as a chant before show. Lots more in the DVD so nab it if you are able to. Keep in mind that acting is objective, I try to mold actors into actors that owners like as opposed to actors that are the scariest things ever, scary is important and I never forget that but showing up is more important cause if you miss nights or if you miss groups you did not scare those people at all.
My advice is from 10 years in year round haunts and from working in different seasonal haunts all over the country, I have done it long enough to see patterns that you do not catch onto until you have scared your first 500,000 people or so.
Allen H