The most important principle of room design is function. Knowing how you will use a room before you begin the design process ensures that it will work for your particular lifestyle and intentions. Whether you are designing a formal dining room you won't use often or a living room that has multiple daily functions, proper planning allows you to make the best use of your space.

There is no right and wrong base color for your room, but you'll want to take some factors into consideration. If you have existing items, such as a rug or piece of furniture you plan to use, find some colors that coordinate. If you are starting from scratch, you can choose from any color you love. Bold can be fun and makes a statement, but think about whether you'll get tired of something bright or really dark, and try to choose accordingly. Once you've settled on a color range, pick up some sample pots. Paint stripes of a few different shades on your wall so you can see how they look throughout the day, in different lighting.

Balance doesn't mean mirroring everything, it simply means arranging the room so that each area has proper weight. This may require multiple conversation groupings in large rooms, or placing a specific piece of furniture as the centerpiece and designing the room around it. A room with balance should feel calm. If something seems not quite right about your design, it may be out of balance. Try adding a mirror to a blank wall or a rug to anchor your furniture and see if you like the results.

If your room has an existing feature, such as a fireplace, that will draw the eye, it makes sense to use it as the centerpiece. Fighting against a strong architectural element you're not crazy about will make the room seem out of proportion. Consider if there is some way you can spruce up the focal point — for a fireplace, think painting the bricks or picking up a beautiful vintage screen — so you want to build the room around it. If there is no existing feature, you get free rein to choose the area you want to emphasize. Choose a big, striking piece of artwork above the couch, for example, or a fantastic light fixture.

The finishing touches are what truly make the room, and one such touch is the addition of area rugs. It is easy to avoid using rugs because they can be pricey and you may feel intimidated choosing a pattern or color that works. Don't let uncertainty steer you away from rugs. They are functional— they dampen noise throughout the home — but they are also a great way to define living areas in an open floor plan, carry a color theme from room to room, and add personality to your space.

Harmony is achieved when different elements of a room go together. That doesn't mean that everything needs to match, but they should have some common element, whether it is size, color, or texture. Harmony creates a feeling of restfulness, so you want more harmony in sleeping areas, while you can be more adventurous in living spaces. Keep in mind that if you're a bohemian at heart, harmony in texture could just mean prioritizing a variety of textures!

One sign of a well-designed space is contrast that works. It is tempting to add items that obviously match each other as a way to stay safe in your choices. The addition of contrast shows confidence in your design. You can add this element through color or texture. Adding throw pillows that match an otherwise subtle accent color from the rug is one savvy way of incorporating contrast.

Think about proportion and scale. These two concepts are similar, but proportion considers how pieces in a room relate to one another, size-wise, while scale focuses more on how each item relates to the overall room. While large pieces in a small room are an obvious issue — having to squeeze past anything is a design no-no — smaller pieces in a large area can throw off the design as well. Adding more furniture to fill the space can make the room feel cluttered. It is better to choose furniture that fits in the room. If you are working with existing pieces, understanding if the scale is off can help you make better choices when accessorizing.

Repeating shapes, colors, and textures is an easy way to create a unified theme. Consistent design elements give the eye space to rest and make your design choices look intentional. If you are going for a maximalist style, selecting a shape or color to repeat prevents the area from looking chaotic, an issue that can seep from the decor into the mental states of the people in the room.