Try to limit the amount of bubble production when steaming your milk, you can control this by adjusting the depth of the steaming wand. Closer to the surface = more/bigger bubbles.
Make sure your steaming wand is NOT an auto frother. It’s almost impossible to get good microfoam with an auto frother.
After steaming, tap hard on the counter a few times to pop the biggest bubbles, then swirl for about 10 seconds to homogenize.
Here are a few tips which you might find helpful.