The best angle for taking a selfie on a smartphone is to tilt your head slightly and raise the camera up so you're looking down at it. This helps avoid any double chin issues and ensures that your whole face is visible in the frame. Experimenting with different angles can also help you find what works best for your selfie. Holding the camera above your head or angling it slightly downwards can produce different effects and flatter your features in different ways. Ultimately, the key to taking a good selfie is to find a pose and angle that makes you feel confident and comfortable.