To begin with proper preparation, you have to be knowledgeable of the substrate you are applying to. Pressure washing your project area is your first step – be careful that you don’t apply to much pressure to wood siding, as it could damage the surface. Once your surface is cleaned off, scrape off and sand any excess paint remaining. Choose a proper primer for your substrate – use a quality masonry primer if it is Stucco, CMU block or brick, or use a quality primer for a wood substrate – I like Zinsser 1-2-3. Once you have a good bond established, caulk your cracks using a good quality product. Not a big fan of the DAP Products, my personnal favorite is Big Stretch or SherMax from the Sherwin Williams Company. These caulks will flex with the weather changes and give a longer life than the cheap products. Never go cheap if you want a long finish life with your painting project – it always pays for itself in the long run.