If your smoothie comes out too thin and watery, adding some dairy-free yogurt can help to thicken. Coconut yogurt or soy yogurt are both great options. For the creamiest smoothies, frozen fruit works best whether that's using a frozen banana or adding frozen berries to the mix. As a last resort you can add ice cubes. Just keep in mind that as they melt, the smoothie will return to a more watery consistency.