Hi! To create the illusion that your space is even bigger than it actually is, there are many things that you can do. Two of my favorites are to hang your window treatments (blinds, curtains, etc) about 1-2 inches above the actual window molding, and incorporate mirrors. This will make your ceilings seem taller. Here are a few of my favorite bright, colorful window treatments:
http://www.deciture.com/shop/decor/7/modern-twist-geometric-curtain-panel/

http://www.deciture.com/shop/decor/7/world-beat-yellow-curtain-panel/

As for the mirrors, what this does essentially is reflects light in the room as well as the room as a whole and makes the area appear better lit and larger. Here are a few choices:

http://www.deciture.com/shop/decor/7/antiqued-copper-mirror/

http://www.deciture.com/shop/decor/7/hayes-arch-mirror/

http://www.deciture.com/shop/decor/7/distressed-windowpane-mirror/




Note that the larger and more divided the mirror is, the bigger the room will appear, which is why I attached mirrors that are divided in some way or another.

Good Luck!

Good advice from Warner above, also try to stick with a palette of colours that's re light and similar. It doesn't have to be boring because you can vary tonally.Also paint the ceiling two tints lighter than your walls to also add height

Thanks for your comments and advices .I want to do experiment with ceiling colour and want to give bright shade then pl advice in that case also may i be able to create the illusion of bigger room?