Fill your blender with ingredients in the order listed - frozen fruit, avocado, yogurt, and peanut butter. Fill with milk until the fruit is nearly covered.

Start blending on low. If blender “stalls” mix with agitator if your blender comes with one, or stop and mix with spoon. Watch how the smoothie moves in the blender. If it’s moving well, you can amp up the speed. Otherwise, keep mixing at lower speeds until it moves better. If you stop the blender, work your way back up to higher speeds. 

Once properly blended, pour into cup or bowl of choice and enjoy! My Vitamix usually takes ~1 minute of blending slowly increasing speeds with occasional assistance from agitator.