A few tips/notes:

• I’ve gotten in the habit of slicing bananas and freezing them in an airtight container. I lay a sheet of parchment paper over the slices of one whole banana, so I know how much to use for each smoothie.
• Nut butter: use what you like. I always buy/use salted.
• Depending on the size of the Medjool dates, you may only need one. If you like things a little sweeter, you may need two. You may not need them at all. My blender is old and does not do a great job whirring ingredients into a smooth purée, dates in particular. If you have the time, you can soak the dates in the almond milk, which softens them and makes them purée more smoothly. I do this first thing in the morning: pour a cup of almond milk into a 1-cup liquid measure; break up my date and drop it in. (UPDATE: I splurged on a Vitamix, which makes the whirring process a whole lot easier.)
• I bought hemp seeds on a whim after reading about them in books and blogs, and I now add a tablespoon to each smoothie. Hemp is a good source of omega-3 and omega-6 fatty acids, contains iron, magnesium, and vitamin E, and is a complete protein.
• Chia seeds. I always have chia seeds on hand because of this muesli, but I now add a tablespoon of chia seeds to each smoothie as well. Chia seeds have a high amount of omega 3 fatty acids, fiber, minerals, and are also a complete protein.