Your phone is a cesspool of germs. But you can easily fix that. The best way to clean most electronic surfaces: 70% alcohol. use a tissue, cotton swab or buy the wipes format and just go over your screen and around your phone. Rubbing alcohol evaporates quickly, making it a safe choice for pricey tech.
Be sure to avoid aerosol sprays, bleaches, and abrasives which will damage your phone.