2) Figure out framing and focus. Flip your camera vertically, but be ready to switch to horizontal for the finale, when the fireworks will take up more of the sky. If you're including a foreground element, make sure the horizon is level. Use manual focus to ensure sharpness. When the first blast goes off, check to make sure you got the focus right, then check again occasionally during the show.
3) Experiment with exposure.** Use manual mode. Longer shutter speeds will record bigger radiating trails, so try shutter speeds of 2–8 sec with apertures between f/8 and f/16 at ISO 100. If your camera allows, auto bracket your exposure and shoot RAW files to give you more to work with later. And play with super-long shutter speeds (30 sec or more) to capture multiple explosions in a single frame: Use the Bulb setting with a remote release to keep the shutter open, cover the lens with black cloth after a shell bursts, then uncover it when you hear another shell going off.