How do I write a zombie book that only focuses on the characters surviving without making it boring?

The question why should always precede the question how? “…….without making if boring?” That may be impossible, since the zombie fantasy is a dead horse that has already been beaten till it stinks.

But, if you are published, insist on paperbacks only, with a minimum of colored ink and glossy paper on the covers. The rest of it will be less toxic and biodegrade much faster in landfills.