Summarize:

Nudes, pale pinks, and shades similar to your skin tone will actually make your lips look larger. Darker shades can flatten your lips and make them look smaller. If you can, pick lipsticks and glosses that claim to be "hydrating." Keeping your lips moisturized and hydrated is a huge part of helping them look big. Dry lips get wrinkled and look smaller.
Opt for lighter colored lipsticks to make your lips appear bigger.