You have to do all the steps in painting process in order to make it good and longlasting.
Cleaning - All surfaces need to be well cleaned from dust, dirt, stains using power-washer if needed.
Preparation - We examine the house in detail to discover all cracks and damages that need to be fixed before we put on paint.
Painting - It is necessary to apply 2 or more coats for outside painting jobs. Don't let someone told you 1 coat is enough. They don't know what they are doing.