When applying polish, it's important to let one layer dry completely before applying another. It's also important to apply polish in thin, even layers. Not only do thicker coats take longer to dry, but they also trap solvents in tiny bubbles during the drying process.
Make sure you're not sitting near a fan when applying polish to your nails. A fan helps solvents evaporate faster from the top layer, but can't reach the layers underneath. This results in trapped solvents, which causes those tiny bubbles.
If possible, keep the room between 68-72 degrees Fahrenheit. As long as you'e not sitting near the vent, this can also help prevent bubbles.