Picking a sofa that you love is one of the first places to start. A sofa is usually a focus point in a room. Measure the space that you have and take some time to think about materials (fabrics, leathers), colours, shapes (sectionals, loveseats) and finally your budget.
When it comes to the whole room a quick rule is to pick a few colours (3-4 to start) that compliment each other and stick with them. Don't be afraid of using strong bright colours or patterns either. Choose which colour(s) are the main colour(s) of your room and which are accent colour(s) to be scattered here or there in the form of cushions or fresh flowers.
What is the focus in your room? Do you want everyone to notice your gorgeous new fireplace or is the furniture the focal point? What is the function? Is it a room TV room for your family of young energetic children? Perhaps the pristine monochromatic white look that you love is not the most practical, but you could always compromise by adding plenty of white accessories.
Ask yourself these questions while you do a little research. Look through magazines or go online. There are plenty of bloggers out there with fantastic style ideas! Clip the pictures you like and go from there!