Paying attention to temperature and sanitation are the two most important things. Also, if you're going to do a protein rest, keep it on the shorter side (15-20 min.). I usually do a step mash at 122 for 20 min, and then ramp up to 146-149 for 60 min. Both pilsners I've done have had excellent head retention, with pilsner malt being the only malt.