Things You'll Need
Instructions
Print out in advance any handouts or visual aids you plan on using for the campaign. Use things like old newspaper articles, knick-knacks that look obscure and/or steeped in the occult, and journal entries on faded paper.
Give the characters a compelling hook to investigate the bizarre occurrences that will populate the campaign. Use elements like the desperate and mad ramblings of an old friend who has been driven insane, or mysterious letters mailed from arcane organizations, to draw the characters into the story.
Remember to keep the focus of the game on investigation, research and exploration. Keep the tame and calm scenes going for as long as possible, so the weird and violent scenes have more of an impact.
Once the story starts to lag, inject terrible old curses, murder most foul and horrendous monsters that defy imagination.
Keep in mind that the characters are normal people who would probably be messily eaten by huge monsters if they attempted to fight them directly. So give them some other way of overcoming evil creatures, such as banishing spells or a means of simply escaping the situation.