Feel free to use any type of orange you prefer! Mandarin oranges will give a much sweeter flavor, and blood oranges make blood orange vinaigrette with an incredible red color.
You can adjust the amount of sugar as you desire, depending on the sweetness of the fresh orange juice.
If you don't have any fresh oranges, you can use bottled orange juice, but the flavor won't be quite as good.
Quality extra virgin olive oil will go a long way in homemade vinaigrette recipes!
You can swap out the orange juice for lemon or lime, or a blend of all three. Just be sure to taste the dressing and adjust the sugar!