Firstly you will save a great deal of time - and even money - trying to source items that you think will go well together. Secondly you will be guaranteed a finished look that is both stylish and coordinated; in other words there is no chance that your 'mixing and matching' will go wrong.
These worries are entirely unfounded however if a couple of rules are abides by. Firstly it is necessary to keep a theme running through every item as mentioned above. Oak living room furniture sets can be matched with items made from mahogany if both pieces feature a natural wood grain as this then becomes a recurrent theme.
Choose a focal point. Choosing a focal point in your living room space is important as you want to accentuate the best features of the room. A window is a great feature in any living room space both for the view it may have and also the light that it lets in. If this is your focal point arrange the furniture near by and make sure both you and your guests can enjoy the view/sunlight. Other focal points in the room include an entertainment unit or a fireplace. These areas in the room should be accentuated as well.