1. Check where the failure started
Look for peeling paint, chalky areas, hairline cracks, damp marks and failed sealant. Do not simply cover the symptom. Moisture or movement should be understood before coating.
2. Clean the surface properly
Dust, salts, mildew and loose coating reduce adhesion. The cleaning method should suit the wall and its condition, followed by enough drying time.
3. Repair and prime
Open and fill suitable cracks, patch damaged areas, sand rough edges and use the correct primer where the substrate or old coating needs it.
4. Choose a sensible weather window
Avoid painting a damp wall or rushing between rain. Surface temperature, wind and drying conditions all affect the finish.