There are six universal rules to be followed always in interior design. Following this simple rules, will save you a ton of time and brainstorming.
In every room, have to be chosen one or two central points of interest before starting to decorate. It can be any large item in the room that attracts attention. The sofa area with a special table in the middle can become a central point. Choosing a central point to help the room to not get too crowded, since all additional elements will draw attention to them.
Interior Design

The proportions must be taken into account when we consider the size of some objects in relation to other objects in the room. For example, a large piece as a piano located near a huge sofa would look disproportionate in a small room.

There are two types of visual balance: symmetrical and asymmetrical. For example, you can place on a table two candles, each on one side of it. This is a symmetrical balance. The two candles represent each other’s mirror image.

The asymmetrical balance is made when two different objects are placed symmetrically. For example, using the same table, you can place a candle on one end and a long thin vase in the other end. Both are placed symmetrically to each other, but are not the mirror image. However, the size and location in which they are placed will balance the space.

The contrast brings the surprise element in the room. While the furniture must be all the same style, the accessories can introduce various color accents or forms which contrast with the rest of the room.
It refers to visual repetition in the room. The room needs contrast to be surprising, but also needs repeating similar elements. The rhythm can be made using the same prints or colors in various places in the room. For example, the color of the table lamp can be found on the cushions on the couch.
Harmony is achieved when all the decorations fit perfectly. The elements used in the room should match in terms of size, of visual interest by contrast, without forgetting the rhythm of the room. The accessories must be in perfect balance, wherever you place them.