1) First, gently remove nails and screws with the reverse side of a hammer.
2) Fill any small holes and tiny cracks with a quick drying filler from the hardware store.
3) Clean walls are really important. Wash them with sugar soap from the hardware store (or a mixture of warm water and gentle surface cleaner). Rinse with clean water afterwards to remove any soap residue.
4) Brush the walls lightly with medium or fine grit paper from the hardware store. Now you have a smooth surface.
5) Newly plastered wall or unpainted surface? You need to apply a ‘mist’ coat before you paint. To make a mist coat, mix equal parts paint and water. Apply one coat of this to the unpainted wall. Now you can start painting!