Keeping your plant in an appropriate size pot is always helpful for air flow and water drainage. When watering as a seedling it is best to spray it with a bottle. This adds oxygen and gives even dispersement. Its also difficult to over water that way. As for direct root effect, there are root boosters, both organic and chemical. There are also household items like egg shells that contribute to healthy root growth while adding calcium. Of course when you add anything you need to be sure you dont over load it with nutrients causing nutrient burn. You also have to factor in ph balance. For example, egg shells contribute an alkaline ph to the soil and you want to stay on the acidic side. At the end of the day, it comes down to style and preference as much as what you have and where in growth period you are.