To prevent eggs from cracking while cooking
I used the method here before with good success: http://simplyrecipes.com/recipes/how_to_make_perfect_hard_boiled_eggs/
Basically you start with the eggs in the pan with cold water and bring the water to temperature, right when it reaches boiling you pull the heat back and let the eggs cook for 10 minutes.
You don't need a full on boil to hard boil the eggs.
between full boil and half boil to avoid cracking n wastage
mid heat for 5 mins then low heat for 7 mins (turn the stove switch to the left)
To prevent shell from sticking to eggs
Either leave it in hot water then cool
Or put the eggs in cold water then peel immediately