Here are some tips and tricks on interior designing, that will help you in the job. You can plan the design online or on paper. There are many sites which will allow you to design a room for as less as 50 bucks. However, with some basic sketching you can create your own plans and don't have to design a room online.
This will give you an idea of how much space is available in each room. So, draw rough sketches of each room, and draw the permanent elements in the room in a top angle view. Keep photocopies or scans of these drawings if you want it as a backup.
Theme and Focal Point
Now, consider the whole house as one whole unit, take a walk in different rooms and visualize what all can be done to design the rooms. You can contemplate on a single theme to decorate the house. This is important as a theme brings a sense of harmony to the house.
Then start drawing on the room sketches, the main elements which are necessary in the room. At this point of time keep in mind the focal point in the room. For example, when it comes to living room you can consider a fireplace or a flat TV as a focal point and arrange furniture around it.
Symmetry or Asymmetry
You can create a symmetry by arranging things placed on the opposite sides in an identical way, or create an asymmetry by using curves or placing objects of contrasting colors or different sizes. However, make sure everything looks well-balanced.
Take care that the furniture elements have edges which can be curved or sharp, that can match other elements in the room. For kids bedroom interior, go with softer designs and light colors.
Finally, comes adding accents. These help to give a final touch to the room decoration. Keep it simple to match a simple and small room, for larger room, consider placing flattering large accents.
Make sure you have enough cabinets in your house to keep your room look neat and tidy and let the room interior be displayed. Having enough cabinets will help to maintain the clutter, which will go on accumulating with time.