Cleaning the surface needs to be done before any repairs and before applying an undercoat. It's essential that surfaces are cleaned before painting, even if they don't look dirty, as residue from regular household cleaners can stop the new paint from properly sticking to the surface.
In general all you're going to need is sugar soap, a big soft sponge and a clean bucket, however some surfaces might need sanding. Peeling and flaking paint also should be removed by sanding and scraping, and make sure the sugar soap is totally washed off the surface prior to painting.
The most common interior surface is plasterboard or Gyprock. First it needs to be dusted down, then any mould, dirt and grease removed by using sugar soap and scrubbing, then rinsing with clean water.
Bathroom and Laundry
With bathroom and laundry surfaces, mould can be removed by mixing one part bleach with three parts water and scrubbing. Next rinse and apply an anti-mould preparation product, then allow the surface to dry thoroughly before painting.
Masonry includes cement render, brick, fibrous cement sheeting. It should be allowed to cure for 28 days if new. Then simply follow the instructions as above.
Timber trim, doors and any shiny surfaces are a bit more tricky. They might need to be dulled by sanding and sharp edges also need to be sanded down. These surfaces should then be cleaned.