Heavy cream and half and half will add richness, but its okay to use milk if you don't have cream in hand.
Bread should be at least a day old and let it rest on the countertop loosely covered to dry out. If the bread is not dry, toast will become soggy.
The type of bread used makes a difference. Try using one with a slightly firm texture. But if you don't have it, go ahead and use the one you have handy.
You can add 1/2 teaspoon of vanilla extract or cinnamon powder to the custard.
You can make the milk and egg custard overnight and keep it in the refrigerator.
If you are not a big fan of sweet, substitute honey with a pinch of sugar and serve it with ketchup.