To substitute honey for (granulated, white) sugar:

Use 3/4 cup honey for each 1 cup of sugar.
To adjust for the added liquid, reduce the other liquid in the recipe by 1/4 the amount of honey used. (So 1/4 cup for each cup of honey used, or 3 Tablespoons for 3/4 cup.)
If desired, add 1/4 teaspoon baking soda per cup of honey used, to counter its acidity.
Lower the baking temperature by 25 degrees F in baked goods.

To substitute stevia for sugar:

Stevia is very different from other sweeteners, and tricky to substitute. It is dozens or hundreds of times sweeter than sugar, and lacks sugar’s bulk and capacity for crystallization.
If your product does not require bulk or crystallization (sweetening a drink or yogurt, for instance), stevia is a good choice. Follow the instructions for the type of stevia preparation you have.
If you are attempting baked goods or something else that does require these traits, your best bet is to use a recipe created specifically for stevia, or to use it only in combination with another, bulkier sweetener.

To substitute maple syrup for sugar:

Use 3/4 c. maple syrup for each 1 cup of sugar.
To adjust for the added liquid, reduce the other liquid in the recipe by 1/4 the amount of maple syrup used.
Be aware the finished product will have a slight maple flavor.

To substitute coconut sugar for sugar:

Substitute 1:1.

To substitute date sugar for sugar:

Substitute 1:1. (The texture is very different, so be prepared for texture changes.)

To substitute fruit juice concentrate for sugar:

Use 3/4 cup juice concentrate for each 1 cup of sugar.
To adjust for the added liquid, reduce the other liquid in the recipe by 1/4 the amount of concentrate used.
For baked goods, you may need to reduce the oven temperature as for honey.

To substitute molasses for sugar:

Use 1-1/4 cups molasses for each 1 cup of sugar.
To adjust for the added liquid, reduce the other liquid in the recipe by 1/4 the amount of molasses used.
If desired, add 1/2 teaspoon baking soda per cup of molasses used, to counter its acidity.
Be aware that molasses has a very strong, distinct flavor. (This is a better substitution in baked goods with a hearty flavor.)

Be aware that sweetener substitutions (3,4) will typically result in some changes to the taste and texture of the food. It’s worth experimenting with, for the sake of your health! Just don’t expect to obtain an identical result.