Hello Suryaprasad,

Preparation of surface for painting is following.
1) Wood Work
• The surface should be cleaned of dust, mortar droppings and splashes of cement slurry etc.
• The wood work to be painted should be dry and free from moisture.
• All unevenness should be rubbed down to smoothness with sand paper.
• Knots if any should be covered with putty of same color.
• Priming coat should be applied before painting wood work.

2) Iron and Steel Surface
• All rust and scales should be removed by scraping.
• The surface should be cleaned of dust mortar dropping rust etc.
• Priming coat should be done on the surface with good quality of primer.

3) Plastered surface:
• The painting work should be done after the wall is completely dry.
• Surface should be cleaned of dust, mortar dropping splashes of cement etc.
• Holes and undulations should be filled with putty and rubbed with sand paper to make the surface  smooth.
• d) Primer coat should be done on the wall with good quality of primer.

Thanks