A lot of the best horror movies aren't going to be enjoyable if you're not used to watching good movies. I don't mean to sound snobbish but you sort of need to build an appreciation for good filmmaking in order to get what a lot of movies are going for. That said, watch Alien or The Thing.
His House- blends psychological horror with supernatural elements to make a really poignant story Cat People- kind of cheesy but interesting to watch for what it gave to the genre The Bad Seed- Set the framework for the evil kid trope and does it well Crimson Peak- More Gothic than Psychologic but still really good Last Night in Soho- Great Cinematography/Special effects The Hunger- Interesting exploration of Vampires with Psychological Horror (Also David Bowie for a bit)