Global Health Informatics is an emerging field, as demonstrated by several substantial and widely used electronic medical record (EMR) systems along with the emergence of mobile based or"mhealth" systems. We describe here many of the practical lessons we have learned from implementing systems in a wide range of challenging environments over the last decade. Some requirements, like data backups, skilled staff and local leadership are universally important. Others, such as limited power, poor network access and distributed populations, require different designs and strategies in resource poor environments.