Horror film Trailer
 

I am writing a Horror Film script and keen to come up with a script for a trailer for the same. any resources or samples or ideas how to go about it.

Read some books! Seriously, there's a ton out there. Read about what has been done, what works, what doesn't. What sub-genre of horror do you want to add to? If it doesn't add to the genre, don't do it. If it takes an old idea that worked, put a twist on it that relates IMPORTANCE. This is how An American Werewolf in London gained popularity: IMPORT. Want to have a great trailer? Add a dash of sentiment, spice with curiosity, and top it all with production value(including gore?). There are a ton of variants to consider here, so write them out for fun, mess around, get dirty!