Though a green smoothie can be stored for 2 days I find that the colour changes. Being a visual person I find it difficult to drink the smoothie. I prefer to make mine fresh.
Protips
For a mild/ no spinach taste to your smoothie maintain this proportion always. For every 4 portions of veggies add 6 portions of fruit.
A smoothie needs to be smooth, So devein and blend the veggies first.
You can always use natural sweeteners like honey, maple syrup. However consider using mangoes, berries, pitted dates to sweeten your smoothie.
In place of water, you can always use coconut water, plant-based milk.
Freeze the veggies and fruit so that you have a chilled glass of smoothie.