Some Tips are:

• Selected paint colors may look different in different lights, both at daytime and at night. So, you should choose the paint according to look of the room in different lights and according to the function of the room.
Dark and warm shades such as red, orange, yellow and even dark shades of navy blue make rooms look smaller while light and cool colors make the room look larger. Best colors for small rooms are white and light and pale neutral.
Alkyd or oil-based paints are good for wooden painting and does not leave it sticky in winters but latex or water-based paints dry faster, can be cleaned with soapy water and does not turn yellow easily and therefore they are better for walls.
Look at the exposure the room has, as lots of sunny southern exposure may be a good spot for cool colors while a shaded and northern facing room best suit with warmer shades.
There should be some relationship between adjacent rooms and the new paint color for the flow and link.
Since colors affect the mood, choose relaxing soft colors for bedrooms and exciting colors for kitchens and dining rooms.
• Generally ceilings are painted in pure white, off white and highlighted/tinted white colors to make them appear high and make the room look open but if ceilings are high enough, one can use medium dark colors to make the room look warmer and comfortable as they tend to make the ceiling advance to the eyes of the viewer.
Determine the color scheme of the room according to furniture, window coverings (window blinds, curtains, etc) and certain accessories of the room. To add bold colors to the room, use a darker shade to paint the trims than the walls.
Ask the paint stores for the exact amount of paint you will need for the calculated area of wall for the room and number of coats you are planning for. Since blue and yellow colors need more coats, you will need more of them if you are using them.
To soften the look of a bold color on walls, you can try rag rolling, sponging or color washing the walls using a light, soft shade.