As someone who has DM'd CoS, and specially Death House, I'll add my 50 cents specifically for the scenario you described, while trying to generalize it. I find my answer pretty similar to Szandor's answer, but I think adding examples from the adventure you were running will help.
Also, I'll obviously put the disclaimer: THE ANSWER HAS LOTS OF SPOILERS ABOUT THE DEATH HOUSE.
Prepare a lot
Some adventures require more preparation than others. Sandboxes usually require more preparation, as you need to understand the general concept of everything in the area the players are, since they can go anywhere. Curse of Strahd is such case. Even Death House, which is a railroad adventure (it's suggested the players are forced to enter the house if you go by the book and they can't do anything but explore it to the end), has too many details for a (supposed) one-shot adventure.
Recently I'm running LMoP and it's so much easier, even being a sandbox as well.
The point is: you've got a tough one in your hands. When you come across with a similar one, read the adventure as many times as you might need until you feel you can do it by head.
Page 216 from the CoS gives you a complete map of the Death House. Most of the relevant details are actually included in it and help you remember what is in each place. If you have a hard time understanding the drawing by itself, read the section about the area while seeing the map for that area. That visual memory should help you to remember the details.
Many published adventures (which the question is tagged as) (at least from D&D, which your question is not tagged as, but your problem is), and specially hardcovers, come with such detailed maps.
If you are a good drawer, you can make the map yourself and add the details you want to remember. You can also just note these details with letters/symbols if you want, instead. Make something simple ennough that you can understand and remember by just seeing it.
What's the point?
I would say this is the most important section of my answer, btw.
For Death House, it's a great hook for CoS because it sets the tone of the adventure. You want to make them scared. You want to be clear that the adventure is often over by a TPK rather than by winning. The second thing you want to say about the Death House is: it's old. Nobody lives there for years. These are the two messages you want to deliver in the Death House. (The old is specifically for the Third Floor, as the first two are under magic effects that make them look new.)
Which details actually help you to deliver what you want and which are... actually useless?
Also, how many times do you need to include these details?
For example, every room in the third floor talks about dust, cobwebs and other signals of age. When I was playing it, my players interrupted me saying "ok, we already know everything here has dust and cobwebs. Tell us when it doesn't." (I don't mind being interrupted if they are getting bored :P). That's a signal that some details get boring when repeated.
As an example of details that don't help to deliver the message at all, the Spare Bedroom (19) states
This web-filled room contains a slender bed, a nightstand,
a rocking chair, an empty wardrobe, and a small
This helps with the immersion that this is a house where people used to live, but that's all. You could just describe your own guest bedroom, your own bedroom, anything you wanted here and achieve the same thing.
In general, think about the point of the adventure/place you want to make. Is it a dungeon crawling? Then usually the players are more worried about the Goblins they are going to face than the details on the walls. Is it a terror adventure similar to Death House? Focus on the details that instill fear and shadiness. Is this a dragon's lair? Put dragon things - bones of eaten cows, hoards of treasures. Archmage tower? Spellbooks, spell scrolls. You got the point.
Have a cheat sheet
Which actually can be the book opened in the relevant chapter of the adventure. I have some ability to multi-task, so while my players are talking and thinking about their actions, I'm often reading the book sections about near areas. Sometimes I screw up and either lose concentration and have to ask them to repeat though, so if they mind it just don't do it and have a smaller cheat sheet including the details you think are essential.
I've mentioned in the Spare Bedroom that you could describe any bedroom and would get the same effect - so, if you don't remember the specifics about this bedroom, just do it. Describe something else. Obviously now you need to remember whatever you described (mainly if they are coming back), but you should be able to. Write down in the cheat sheet the new features of that place if you think something is really important.
I messed up, now what?
Well, Death House is easy on that. MAJOR SPOILER AHEAD
After you deny the cult (implying the players will, since sacrificing someone is usually not the way to play it) the entire house changes anyway. The doors becoming Scythe-blades should worry your players more than that wardrobe having 2 doors instead of 3 now. Even if you burn the house down, it comes back. Obviously things that aren't exactly explainable are happening here. Some things should worry your players more than others.
If you don't have that freedom... Well, people make mistakes. Someone as genius as Tolkien has inconsistencies in his works. Don't expect to be perfect. Try your best, but you and your players should know that sometimes you will mess up and forget you had put a table there.
After the session, one of the players even said in a not-overly-impressed tone "we just spent the last out-of-game hour or so exploring rooms".
That's on them and on the adventure. You might have failed to deliver the message about fear and oldness, but spending too much time doing something not needed and not liking it afterwards is usually more a player's problem than yours.
As a second side note, talking from experience, throwing a player in CoS as their first adventure was one of the worst things I've done.