Plan your room before shopping
One of the mistakes that most people made is that they did not do any careful planning before going out for furniture. The degree of planning also varies a lot depending on how much time you want to spend on planning and how much money you are going to spend on furniture. Measure the spacing before you buy is the very basic step you can take for planning.
More complicated planning, however, is better to be executed by planning tools. For example, you want to preview the color options and try different layouts. Now, IKEA is offering free planning tools for rooms like kitchen, bedroom and office, you can go to their website at IKEA.com and try it out.