I want to be a fan of vampire movies, but the writers keep ruining the story with unbelievable twists. Clinging to the mythology rather than updating them to conform with something at least remotely credible spoils the plot. Let me offer some instruction for all the aspiring screen writers out there.
First, vampires have very long life spans, say around 1,000 years. This is because they are immune to most diseases and have very rapid cell regeneration capability. This gives them the appearance of being immortal. They are sensitive to sunlight, but don't explode or burst into flames when exposed to it. They prefer the dark. If sunlight were fatal to them, all our hero would have to do is find their lair and bulldoze it during the daytime. Not very exciting. Silver is toxic to them, hence the silver bullet thing. The wooden stake through the heart works, but our hero finds out during the course of his adventure that any stake through the heart will do, wooden or otherwise. Holy water doesn't work. Our hero discovers that the source of the holy water that started this myth happened to have very high silver content. The cross or crucifix thing doesn't work at all.
Vampires eat a lot of raw red meat. Blood is very nutritious and a big part of their diet. Most vampires go about their lives without bothering anyone. They work at night and stay inside most of the day in their dimly lit homes. A few socio-paths among their ranks do feed on humans. These are the ones our hero goes after. There has to be some explanation for why vampires haven't overtaken the human population. For one the gestation period for vampires might be very long, or they're not very fertile. The myth of people turning into vampires after being bitten wont fly. The vampire population would have exploded too fast. If you get bitten by a vampire, you just die. Maybe to make it more dramatic you die slowly and go insane in the process.
The movie has to be entertaining of course, so our hero wants to perpetuate the traditional myths to add an aura of the supernatural to his endeavors. He has a crucifix that emits a laser that simulates sunlight when the button on the back is pushed. He keeps a supply of silver laden "holy water" on hand and although any stake through the heart will do, he still uses wood. Then of course, he has his silver bullets, but also carries a silver knife, for close quarters combat.
The vampires have another big advantage over humans in that their metabolism is much faster. This means they perceive our movements almost as if we were in slow motion and that they move and react much faster. This also means they need a considerable amount of downtime every day to rejuvenate, especially after a very active period. When sleeping their metabolism slows to almost zero, giving them the appearance of being dead.
Our hero is a bounty hunter by trade and is called upon by law enforcement to help them with serial killings that have the markings of vampire attacks, or when people start going insane and dying of a mysterious ailment (after a vampire bite). Officially the perps are simply termed homicidal lunatics as the police and law enforcement officials don't want to alarm the public or turn them against law-abiding vampires.
Alright, there you go. Now make me a movie I can enjoy from beginning to end.