Part of any great Halloween celebration is setting the scene! One neat way to do so, is to create a window silhouette. Choose a window that has a great focal point to your house and the party. A front window that isn't obstructed from view from the street is ideal too, so everyone walking and driving by can see how spiffy you are ;) Ha!
I have been doing these for quite a few years now. I've had various themes before--witches, pirates, The Great Pumpkin/Snoopy, Sleepy Hollow/Headless Horseman, and the last several years I've been doing a Nancy Drew Mystery Halloween Party--as is my theme for this year which also includes a haunted house so it works well for Halloween. The above silhouette is my front window for this year and a take off on The Hidden Staircase book and I added a ghost to the side behind Nancy Drew.
Black Poster Board
The first thing to do is figure out your design for the window and print it out to use as a guide. I printed mine out, divided it into 4 parts for the 4 areas of my window.
I then taped up my 4 pieces of black poster board into the window and then I used my printed silhouette image as a guide while I drew the outline onto the poster board in pencil.
Keep proportion in mind when doing this! If you happen to have a projector--projecting the silhouette onto a wall where you've taped your paper is much easier and goes quicker. What I do is old school since I don't have a handy projector.
Once you have the desired look, cut out the pieces. Begin taping your silhouette into the window--I try not to use too much tape and tape in areas where it won't show too much like on the backs of strips that are going across the panes, etc.
The key is to layer the tissue and not overlap too much as overlapping shows up darker. Piecing with tissue can be time consuming but it's worth it.
If you want to make a silhouette that you can use again and again without too much wear, you can make it out of felt. I have a red felt banner with black felt silhouette and in a window it glows nicely. If you used yellow or white and then a black silhouette on it, it will look great too and keep nicely.
If you have a lot of time on your hands, fill all your front facing windows with silhouettes for a complete look.