When all else fails, revisit old Troma Entertainment movies.
Lesson learned from: The Toxic Avenger (1985), Poultrygeist: Night of the Chicken Dead (2006)
Every student needs a teacher, or at least an effective curriculum. In regards to making good horror-comedies, if your goal is to create the funniest, goriest, wildest, and most WTF hilarious genre movie possible, consult the school of Lloyd Kaufman, the fun-loving mastermind behind the infamous indie production/distribution company Troma Entertainment.
With their tongues always firmly planted in cheeks, the Troma team specialized in self-aware ludicrousness. Whereas "serious" filmmakers were trying their hardest to deliver fresh monsters comparable to the genre's iconic greats, Kaufman and his colleagues went ahead and aimed for wacky absurdism with 1985's The Toxic Avenger.
And while every George Romero fan with a camera was aping Night of the Living Dead, Troma went for the gold with Poultrygeist: Night of the Chicken Dead, which is about exactly what it sounds like: an outbreak of man-sized chickens that act like zombies and are undeniably terrific.
Sure, Troma movies defy the first rule we presented, about "playing the horror elements seriously," but whatever. There's always room for Toxie and those evil chickens. If you can't scare 'em, make 'em giggle like Beavis and Butthead hearing the word "balls."