When it comes to red, less is usually more.
When using red in your design you will either want it to match with reds that you have already used elsewhere in your decor or to act as an accent.
If you decide to go for a red sofa make sure your space can handle it. High ceilings, muted walls colours and plenty of natural light will help tone down this bold hue. A large black and white painting/image placed above a red sofa can give a dramatic look.
If you want a look that is more subtle think about incorporating some red scatter cushion or perhaps a footstool instead of going for a whole sofa in red. Even small injections of red can add warmth to a room.
Remember, primary hues work best in modern designs, chalkier and softer reds work well in country settings, whilst burgundies and richer tones are more suited to traditional looks. And when it comes to pattern remember that stripes and prints from the same colour family can work well together. The trick is to choose colours that are similar enough so as not to compete with each other.