1 First, clear the area, removing curtain rails and blinds etc, then wash the paintwork with sugar soap. Next, sand the surface before filling in any holes with an appropriate filler. The filler needs to set before moving onto the next step.
2 Sand the whole surface to get it is as smooth as possible, as any flaws will show through the paint. Next, wipe the surface with a tack cloth to get rid of debris and dust.
3 Cover the edges of the glass pane with masking tape; take time to get this right, making sure there is no glass showing at the edge, and that the woodwork is not covered.
4 If painting a new window, or over old boldly coloured paintwork, paint a coat of primer over the surface, then follow with a top coat of your chosen colour (otherwise, two coats of paint), using around a half-inch brush for awkward sections, switching to a slightly wider (max 2”) brush for the rest.
5 Always paint in the direction of the grain, using light strokes. It is essential not to use too much paint on windows, as this can cause sticking, so spread it as far as you can. Leave the window open until the paint is dry.