What do I need to include in my teaser poster?

After analysing a few teaser posters, I have come to realise that the main point of them is to establish a genre and to appeal to the fans of that genre. For example, for a thriller/horror, there will be a typical black background with a fuzzy or no title and perhaps a vague release date. The image will be strong and the definate main focus. However, if it were for a fantasy, there would be clouds and sparkles and typical colours to denote the particular mood of the film. A person or creature would be the main focus and there would be a title or two and a release date in mystical typeface. Therefore, mine will have to have the following codes and conventions:

1. A main focus image, usually a face but not always
2. A black background to denote mystery, fear and death
3. The colour red must be included somewhere to denote murder and death
4. A release date, vague i.e. the year
5. Fuzzy title, not the main attraction on the poster
6. Maybe a reflection to confuse the audience about who is bad and who isn't or for similar reasons/messages

Based on these observations, I will begin to create a poster suitable for my genre of film and to promote it without giving hardly anything away. I want the audience to become curious about the film and want to see it when it comes out in that year advertised (which for me will be 2010). I want my main focuses to be bloodshed, murder, unknown, suspense, death, following and horror.

For the above focuses, I will create a brainstorm of ideas which represent those words which I could use for ideas in my poster.