As with any painting project the preparation is half the task. Stucco is one of the easiest surfaces to prepare as its porous nature provides a great surface for the paint to bond to. A simple power wash will remove most dust and dirt that have settled on your home. Starting at the top and working down is the best approach and you’ll probably be surprised just how much dust comes off with a wash.
After the surface is clean repairing any damaged areas is the next step. Using a small bead of caulking to fill cracks is recommended. Caulking is cheap so spring for the good stuff. A good 35-year silicone acrylic at the very least. Just be sure that the caulking in paintable to avoid adhesion problems later.
If you have any areas where the stucco is falling off this is the ideal time to repair it. I highly recommend going to a specialty supplier to get a professional stucco mix. Unfortunately, just like with paint, the big-box home improvement stores usually don’t carry a very good product. You’ll pay more this way but it will be worth it when you don’t have to re-patch the area a year or two later. Mimicking the existing stucco pattern is tricky and takes a bit of practice. I use a couple different sized putty knives and trowels ranging from 2″ to 9″ depending on the size of the patch. Just remember that you have a bit of time to work with it and if it doesn’t look right don’t be afraid to scrape it off and start over.