Freezing
Fruits
The fruits should be ripe and clean. To avoid plastic waste, I freeze everything else in glass containers, glass jars or other reusable containers. I always peel the bananas before freezing.
Vegetables
I wash vegetables like everything else I freeze and remove the inedible parts.
Berries
For the berries, it is especially important to not to miss the right time to freeze them. If they are already overripe, some of the berries can be already spoiled and destroy the taste of the entire smoothie later on. Unripe berries can taste pretty acidic.
Herbs
Herbs can be frozen individually or as a herb mix. For sauces, frozen herbs are as good as fresh ones.