There are no strict rules when it comes to decorating, what is important is creating a room that not only reflects you but functions in a way you require.
Before you begin the process of decorating a room first you need to gather inspiration and ideas. Look at magazines, books, blogs and websites. Create a folder either on your computer, pinterest or strips torn from magazines of images that grab your attention.
After compiling your images look at them for a common thread, idea and determine your style. This will help when it comes to buying furniture etc. for your room. Start to collate the common thread images together; you will start to see a very defined design style. Normally for most people this style will be a mixture of ideas.
Consider how you will use the room, your lifestyle and practical needs. Look at what hasn't worked in the past i.e. coffee table to big for the room and you keep bumping your leg on it causing frustration? Think how you want the room to evolve, have you kids or do you plan to have kids in the future.
Lighting will help set the tone of a room, consider creating variations in brightness, highlight and shadow within your space. For instance in the kitchen you will need the lights to be brighter than perhaps a bedroom.
Look at what you currently have, furniture, furnishings, objects, photographs, everything and decide want you want to keep, give away, throw away, move to another room, reupholster etc. Take stock and measure all items you want to keep, this will help you with the next step - floor plans.
Draw out the shape of your room. Look at the pieces of furniture you want to keep. Look at your inspiration folder. Decided on what you want to highlight in the room, i.e. fireplace, window and build a plan around this based on all your previous research.
Always set a budget on what you want to spend this will help keep you realistic when it comes to buying furniture for your home, paint, fabric etc. Then make a shopping list of all you need including labor, paint etc.
Now you have an inspiration folder, you know what you want to keep from your old furniture, you have a floor plan and a shopping list - the next step is research. You know what you need and your budget, research what is out there, the Internet is brilliant for his.
With everything now in place plan a schedule when the work will take place. From ordering furniture, renovation, painting, delivery times etc. it will help keep the job in check and not overwhelm you.