Most people love and fear colour. They love to have it but fear making a commitment. There are a lot of rules regarding colour but here are some of the basics.
As a general rule, use a maximum of 3 colours. Any more and your house can look visually fragmented. Keep in mind that using only one wall colour throughout will make your space look bigger. Use an accent wall colour on areas that you want to highlight. If you want to create a mood, paint the entire room one colour.
There are many factors to consider with regard to colour and furniture. Selecting a neutral colour like greys or browns for large furniture pieces will add versatility and longevity. Feel free to go with bolder colours on smaller pieces of furniture like armchairs.
This is where you can go wild because it is an inexpensive way to add a pop of colour into your home. Cushions can be changed with the current trends or seasons. If you have neutral coloured furniture, your space will need some colour!
Same as cushions, homewares can be used to put your design scheme together.
Use the rule of contrasts in determining placement of art. A bold art piece should not be placed on a bold wall colour.
The proper rug can be the X factor in making an average room fabulous. Again, use the rule of contrasts against the furniture that is resting on the rug. A patterned rug goes great with a solid coloured sofa or vice versa.
Cool or warm colours?
Ultimately, it is a personal preference. Whatever you choose will direct the rest of your decor. For example, a cool colour like blue goes great with whites and greys. Warm colours like red compliments nicely with yellows and browns.
These rules are not set in stone because there are many exceptions. That's what makes decorating fun.