The sooner they contact the older generations the better. Many of my primary sources are now dead and they knew things that are not written down elsewhere. Teach them to become subject matter experts in the locality of their ancestors and to understand about juridictional history, as well as the local history of ancestoral birthplaces. Knowledge of the geography, history, and sociology of ancestral communities help explain why ancestors lived where and how they did and why they might have moved, and also where they might have moved. Teach them to publish their works in anyway they can.
Online webpages are the easiest, and reach the most people.
It is not common to get rich selling family books to cousins, but you won't get poor either if you put your results online and let distant cousins print out their own copies of your work.