Most our recipes have cups and tablespoons. Some recipes will have measurements like 1 apple, 1 banana, or a handful of greens (spinach). For fruits with measurements like this, use a small fruit that is similar to the size of a women's fist. The measurements that uses "handful" are often for greens. While some people may not like so much greens and others love it, it is your time to make it your own! Measuring greens (spinach, lettuce, kale) in a big handful or a small handful makes minimal changes to the total calories. The more greens the better!
I hope this helps give a better sense how you can adjust smoothies to your liking without always relying on measuring cups and spoons!