Halloween is the scariest time of year and it is the best time to step out of your comfort-zone of design. Wikipedia describes the history of Halloween greatly.
In design, you can go scary, in between, or not so scary. These are also laid out as most expensive, in between, and cheap. For my decorations, I am going for the 'not so scary' category also known as, the cheapest. I am making my house look like an old abandoned house. How to succeed in that is to decorate with sticks, tulle, and odd vignettes. Sticks: Put sticks where ever necessary. Such as: chandeliers, lay it down on any type of tables, in a vase. When you are decorating with sticks, GO WILD! If you have a sofa table, why not put the sticks in a vase and if you have enough, make them touch the ceiling and span the whole length of the table. Very dramatic.
Tulle: I use tulle every year for decorating. Weather it is Halloween, Christmas, spring, summer, whatever. For Halloween, tulle looks alot like cobwebs. Placing them over a crooked picture makes it look as if it has been up there for many decades. Or placing with the sticks on the chandelier makes a great focal point. Place the tulle all over. You can not go over board.
Odd vignettes: Place furniture where you would never ever place furniture. On its back, side, or on its normal side but placing it awkwardly. The vignette that I am going to try is a story of lamps. Putting lamps at different heights and laying some on their sides and turning on some, it makes for an unusual story. I also am stuffing a coverall suit with cushions to make it look like a man with no head. We have this round-about in our driveway and putting him there with an outdoor lamp will make him look eery. We cannot forget about the outdoors! If you have columns, wrap sticks around them and make it go into an arch.
For the 'scariest'/most expensive: Make columns out of MDF and paint them grey. If you have access to gargoyles, put them on top. (I love gargoyles) Make a gate around your yard out of PVC pipe and wood. Paint black and it will look like a wrought iron fence. You can also decorate with sticks. For the inside: Make it into a haunted house! Make the dining room be the room for butchering and have people in there. How to do so. Table: Put a white table cloth on with either red wine or food coloring stained on it to make it look bloody. Having real knives are not safe, so if you have fake ones that would be okay. If you do not, make sure someone is in there watching the kids so they do not start stabbing each other. Make the chairs be over on either side of the room. Make them look as if they were pushed over or thrown over. And for the buffet, make it have many candles on it. (preferably white) For the living room: If you have a piano, play it up! Have someone to play it or even get music from your iPod and pretend to play. Make this person look dead or dying. Have red cloth on the piano and a 4 candle, candle stick. Make your furniture upside down or on its side. Put pictures on the ground. Put lots of candles. The kitchen is very hard because you need to accommodate food and drinks. Make it into a scary science lab and play up your food and drinks.
Finally for the 'in between,' just combine the two and look around your house for even the simplest of things. I hope this helped!