Preparation consists of a good washing with TSP, trisodium phosphate. This will neutralize any excess PH of the lime and produce a very clean surface. Make sure to rinse very well and rinse some more, the TSP will try to stick around in the cracks and pores of your stucco and this could mess with the primer.
Allow a couple of days to dry!
Now you need to use a good acrylic masonry primer. This primer can take the high PH of stucco. Apply a lot and make sure to back roll (if spraying) to fill in the pores. After priming caulk around windows and doors and any large cracks (anyplace water can get behind the primer/paint).
Now you can paint. I recommend an elastomeric but any good acrylic with a satin sheen will work. Buy your primer/paint from a real paint store not Home Depot or Lowes.