It's not true you dont need to be a dive master or instructor, to be fruitful. make sure you are a season diver yourself and know the in and out of your equipments (Safety first if not need rescue pai sai) and help them during the dive trip and make small talks to build the pathway first and during diving make sure to keep a look out and see if there are girls struggling to dive, can always assist by holding their hand and dive together. the rest is up to your own hardwork liao.