The elements I am talking about are: the function, the mood and the harmony.

The Function
Any room in a house has to be functional. If not it will be of no use to anybody. Only if it functions according to its' purpose it will be enjoyed. Functional actually means that the room should serve a purpose and be comfortable to perform that function inside the room.
A living room is an example of a functional room. Some living rooms are so decorated and pristine, they are never used. It should not be like that. This is, to put it plainly, an interior decorating failure. A functional living room should be in a manner that it is used for greeting and entertaining guests and providing a space for family members to interact, relax and share quality time together. This makes it a functional room because it has a purpose and use. keep this function in mind while decorating a functional room like a living room.

The Mood
The next of the three elements of successful interior decorating is the Mood. If the mood of a room is to be relaxing and peaceful, such as a bedroom, then everything in the room will work toward this mood. If you want a room to be high energy, such as an office or game room, then the elements applied to the decoration and design will set this mood. If you want a room to be bright an airy, then colors and treatments will focus toward this mood. You should know the mood for which that room is created. Then accordingly you have to decorate it. The decoration should be in such a way that it brings the desired mood to the person in that room.

The Harmony
The third of these three elements of successful interior decorating is harmony. Every element in any room of the home, office etc. should work in harmony with the other elements or items, for example colors, textures and patterns in that room. Be aware that this is not the same as neglecting contrasting elements; contrast should also be used. The clue is to make harmony in the room and this should be the end result of combining all the items within it. The way we usually accomplish this is by utilizing a color scheme that uses three colors which are highlighted throughout the room.
These three elements of successful interior decorating should be implemented into your home. This will make it more appealing, enjoyable and brings happiness and pleasure. Thus it is made enjoyable by everyone who uses that room. These elements should be pulled together with the decor to make it a welcoming one to your family and friends.