There are two primary causes for bubbles:
1. Placing the glass too quickly on the screen and not allowing trapped air underneath the glass to escape - In this case, gently lift the glass edge that is closest to the bubble up to the bubble, then slowly and gently lower the glass back down onto the screen. Use the microfiber cloth in a wiping motion to seal the glass and help expel out any remaining air pockets.
2. Debris or other dust under the glass - In this case, lift the glass and use the dust removal sticker to remove any dust or debris. Reinstall once the glass and the screen is clean.