Inside the booth
Reduce accidental blinks in a four-frame strip
Give the sequence a comfortable rhythm.
A blink need not ruin a playful strip, but an entire sequence of closed eyes can be disappointing when the sitter wanted a clear portrait.
Learn the countdown
Run a practice sequence using the actual booth or app. Notice when the visible countdown changes and when the capture occurs. Timing differs between systems, so do not promise a universal rhythm. Offer a quiet first frame before asking for several fast gestures.
Keep prompts manageable
Choose short instructions the sitter understands before capture. Avoid asking them to read a long sign while maintaining eye contact with the camera. Give a natural pause between actions where the system allows it. A relaxed sequence can preserve expression better than repeated urgent commands not to blink.
Review without overcorrecting
Look at the whole strip with the sitter. A blink may be a welcome part of the story, or they may prefer another session. Let that preference guide the choice. Keep the original sequence if you build an edited version, and do not imply that frames from separate sessions were captured together.