First, you must establish is it "true stucco" and not dryvit. Knock on the wall. Does it have a hollow sound? If it does, it's probably dryvit.
Dryvit is a less expensive "imitation stucco". If I'm not mistaken, it's blown onto the wall with a machine where true stucco is spread with a trowel by hand.
Dryvit is also more fragile than stucco, so you must know the difference.
I've recently had the oppurtunity to do both stucco and dryvit within a week of each other.
First, do a thorough inspection of the wall(s) and determine which areas are weakened with cracks and/or gouges. Point these areas out to the home/business owner and write them down on your contract agreement for the home/business owner to sign, so they can't come back later and blame you for it.
Then, I use about 4 gal soap, 1 gal bleach through the downstreamer for light areas. Heavy mold/mildew, get out the x-jet or pump up sprayer, and maybe add a cup or so of trisodium phosphate. Increase dwell time if necessary.
If all else fails, start as far back as possible with your 45 degree tip and gradually get closer as needed for tough spots, taking care around the weakened areas identified in your inspection. If you have a variable pressure wand, try gradually increasing your pressure. You'd be surprised how much these walls will take if they're in good shape. Strengths will vary, depending on age and damage.
Don't let your chems dry on the surface. Keep the surface wet, and rinse REAL good, or else it will dry "streaky".
Hope these tips help. Hopefully, one or more of the more seasoned pros will confirm this advice or shoot it down. Just telling you my method. It seems to work so far. I've not had any problems. Good luck!
Randy