Make sure that you have prepared the work environment for the entire painting process. Do not take any short-cuts with safety measures, such as balancing on tall ladders. Do rent scaffolding if you are going to work on a tall wall. Prepare the surface thoroughly. If the surface has been painted previously, make sure that you clean it properly with paint wash, and do not forget to rinse properly afterwards. If there is algae or mildew on the surface, you must use a cleaning agent that is specific for these. Scrape off any loose paint. If you scrape off so much that the wood surface appears, you must prime the surface before applying the first coat of paint. Do not forget to cover parts of the wall where you do not want the paint to splash (windows, doors, the patio or the house foundations).