How to put the bookshelves neatly?

I think the books on the shelf should be classified and put together according to the nature of the books, which will be convenient to find. However, most people usually make trouble in the future for their temporary convenience. In fact, I think different types of books may need to be placed on every floor of the bookshelf. For example, I will make a classification on my bookshelf, and the nature of the books placed on each bookshelf is different.

I don't think the so-called neat arrangement is just vertical or horizontal. I think these two ways can be combined, and usually this way will look cleaner. Mainly according to the nature and labeling, the types of books placed on the first floor are labeled on the bookshelf on the first floor.

Perhaps this arrangement is clearer and neater. Books on the first floor can be placed vertically, and books on the second floor can be placed horizontally. In fact, this is mainly based on the size of the bookshelf, and it is good to make the best use of the bookshelf.