To add to the description part. One more thing that can help: focus your description on what your pov/main-character sees and less the overall image. People in stress and horror often don't start looking at the overall world, see all the nice details and the walls, explain what plant is standing in the corner and that their aunt also had this one. People in stress often focus on small details and jump around with their focus. A moving shadow over there, a sound behind you, a smell in the air, a flickering light. Nobody stands still for five minutes and describes the floor.
You can also combine those descriptions with actions to make it more active. The shock after the sound, the shadows from the flickering lights make him shudder, the floor moaning under his weight, etc. Don't describe everything at the start but use actions to move the story forward all the time. If it's a later scene, you can also describe the environment during an earlier scene (daylight) and only describe the changes.
Besides descriptions there are two broad ideas I would underline.
1) Knowledge is power. So for horror the most effective thing is to not know something important. What is the motive behind the killer hunting you? How is the monster moving through the base? What is the monster? What is the weakness of the monster? Let the character earn the important information through hardships or even sacrifices. Besides low quality also a reason why many sequels to horror movies fail. We already know the monster and have all the cards in our hands.
2) If it bleeds, we can kill it. Your character needs a realistic (!) way to beat the monster/achieve his goal. It can be a hard one, but it should be clear that the monster is beatable. Suspense is only there if there is a chance. If not, it's just a monster slasher or something many readers will see as "asspull" after the character had no chance for the majority of the time.
In short: describe details in the environment through actions, make your monster/enemy look powerful by withholding important information the character has to work for (in good horror movies (and even some books) you don't even see the monster for the majority of the time but only the deaths at the beginning), give the character a way out that is unlikely but achievable, and extra points if he achieves his goal through a different way that uses the same effect (we know bullets kill it, so the MC uses the shrappnell of a grenade).