I actually looked at a lot of different horror posters to see what I thought worked best for the genre. I plan to adapt this image for postcards, dvd cover art, everything — so truly it will be key art.
I used Photoshop. The original file is 11.5 x 17.5 inches with 300dpi resolution. (It’s slightly bigger than a standard one sheet to allow for cropping.) This tutorial inspired the flames and I used some of my free textures (and some I’ve been meaning to post and haven’t had time for yet) and some textures by Princess of Shadows in addition to screengrabs and on-set stills.
UPDATE: I had a good question come in. Why didn’t I feature the actors’ faces more? The answer is a) it’s not actually that common in modern horror posters to show the actors and b) I don’t have good pictures to use. The on set stills are just too low in resolution. As it is, I think with some clever Photoshop work I’ve hidden the jpeg artifacts, but I won’t really know that unless I have a poster-size print made. Anyways, if I had a time machine, I’d go back to the shoot and hand my multi-megapixel camera to a PA and tell them to fill up the memory card.
FURTHER UPDATE: I was worried that the hidden skull would be too obvious, but it seems to be escaping notice. Did you see it before I mentioned it? Be honest.