Step 1: Materials
These alone won't be enough though, so head to your hardware store and grab a couple cans of the cheapest black spray paint you can get, and one can of similarly cheap red. Snag a can of expanding foam as well (great stuff). A box of 2" nails to hold it all together and you're all set.
Step 2: Gory Juicy Guy
Paint the whole thing black, then before it dries add some red while the black is still wet. The two paints mixing give a charred bloody look, and you can add more red or more black to taste for what you like.
Once dry you can either nail this whole cardboard plank to a tree as a standee, cut it out, or place it wherever you like. Two cans of great stuff would do good for really filling out the shape, but it's plenty creepy with one can. Just don't go for a full sized adult with one can as it'll probably run out 3/4 through.
Credit for this idea comes from the Cockeyed.com "How Much is Inside" adventures.
Step 3: Graves and gravestones
As for tombstones, start breaking down your pallets with a hammer. We won't be needing a saw and the more rough edges your boards have as you beat the boards apart with a hammer the better.
Take a pointy bit of wood and hammer it into the ground with about a foot exposed above ground, and nail together a cross to tape or nail to it. Spray paint this to bring it all to a common color. I made a small sign to hang from the cross and stuck a stake into the pile to complete the look.
For the "stone" tombstone I broke one of the long styrofoam 2x4s into 2' lengths, stuck them together with nails, painted RIP very close, then kept the can farther back to make the foam look grey. Once again, hammer a couple sharp stakes with nails sticking out at the top into the ground, then stick the tomb stone to these. If the nails don't hold the four pieces together well enough some packing tape before paint can hold them together a little more tightly.
Step 4: The monster spider web of DOOOM!!!
Nail a nail into the tree at a good angle, tie a loop in the first end of the rope, and hook it on the nail. Hammer the nail with rope on it down flat on the tree. String the line to the next tree and do this again, making sure to put tension on the line as this will support a lot of the weight on the web and you don't want it sagging. Bring it diagonal and attach it to the tree, then back across to make the bottom line.
Now it should look like a sideways N. Bring it back up diagonal to make an hourglass shape, looping it through the original loop holding the first end of the rope. bring it straight down the side of the tree and nail it in the middle of height of the tree to make the first side of the middle spoke, then nail it to the other side.
Bring the rope back to the middle at either the top or bottom, and use some superglue or fancy knot to keep it centered in the middle. Bring it to the other end,tie it in place, and you're spokes are done.
For the webbing, I just spiraled the line going inward. A little trial and error is in order to find a means of tying that hold the line without slipping much.
Step 5: Giant Spider
He's made with a body of foam and duct tape, I just broke off a few pieces of foam 2x4 and taped over them to get a somewhat oblong shape. Then painted it black, I later added a red duct tape hourglass as well.
Once the body is made you get some pipe insulation and cut V shaped chunks out of it and glue it back together to make the angles of the legs.
Shove some sticks or in my case trim into the body to make places for the legs to slide on. Slide the legs on and glue them in place if needed.
To attach the head I just used twine around the jaw of the skull. I wove the legs into the web some, and used electrical tape to further secure it in place.
Step 6: The Spooky Fence
The first step is breaking the pallets down. The planks of the pallet are then broken some while trying to keep their full length to make them look a little dilapidated and to give them a pointy end to nail into the ground. You then nail a nail into the top of each slat/post and hammer it securely into the ground. Be sure to keep room for walking around vehicles. Stick the foam 2x4s to the exposed nails and spray paint the whole fence. Keep in mind the heavier you lay on spray paint to the foam the more it'll eat it, so don't go overboard. You can use it to make it look somewhat rotted though. You can also tie the foam to the planks to keep the wind from blowing it off the nails.
Some things to keep in mind are that the more ragged it looks the better and making the whole fence line zig-zag some adds to the affect as well.
Step 7: Details, details, details...
To try and lighten the whole thing up some I also made a small cross and wrote "Trick or Treat" on it and posted it by the front door.
Since the fence didn't go all the way to the front door to keep kids out of the display I added some chain between the house and fence, then gave it a shot with the black paint, but left some of the shiny part exposed.
The "Here lies Dracula" sign and stake in the mound was also an afterthought I came up with the dress up the generic cross marker.
We also replaced the front porch light with a red bulb to make things a little creepier.
Step 8: BUT YOU CAN'T FORGET 'OL JACK!
For those unfortunate people who've never made one, you use a knife to cut a "lid" out around the stem, Use a spoon to scoop out all the slimy seed filled bits (you can bake the seeds for snackage), then use a knife to carve the face in it. Pop a small candle in and set it on the porch.
Mine is pretty simple, but a detail I gleaned from looking at others was to trim the skin off the pumpkin to let the candle shine through some. He's chilling out in the freezer until the big night so he doesn't get smelly or soft.
As everyone knows though, once you've done all this and set out your jack-o-lantern you've made an unspoken pact with every kid in the neighborhood that you will disperse candy to costumed kids upon the utterance of the magical phrase "Trick or Treat!", so make sure you're stocked up on candy and keep an ear out for the door if you've got other festivities going on as well.