Liquids, sweeteners, salt and fats

Liquids...Water and milk are the most commonly used liquids. Water gives bread a crispier crust; milk provides a velvety texture and a bit of milk fat.
Sweeteners...Sugar, honey and molasses provide food for the yeast and encourage faster growth. Each enhances the flavor of the bread in it's own way and helps brown the crust.
Avoid artificial sweeteners as they don’t provide the sugar the yeast needs to do the job.
Salt...Salt inhibits the yeast and prevents the dough from rising too much too fast. Forgetting the salt may cause the bread to collapse if you let it rise too long. If you reduce the salt in a recipe, you’ll need to decrease both rising times, too.
It also seasons the finished bread.
Fat...Butter and vegetable oil make bread tender.
In addition to tenderness, butter adds flavor.