1. Use case & goals

• Define primary scenarios (navigation, industrial, medical, consumer, gaming). Hardware and software choices follow the use case.
• Prioritize metrics: field of view (FoV), brightness, latency, battery life, weight.

2. Optics & display

• Display type: waveguide, pancake, microLED, OLED, LCOS — each trades off size, brightness, contrast, and power.
• FoV vs. form factor: larger FoV usually increases bulk and cost.
• See-through vs. occluding: optical combiner quality affects real-world color/contrast and user comfort.
• Eye-box and vergence: ensure comfortable viewing for different eye positions.

3. Sensors & tracking

• Inside-out vs. outside-in tracking: inside-out (on-board cameras/IMUs) is more portable but needs compute; outside-in (external beacons) may be more accurate.
• SLAM and simultaneous localization mapping accuracy are crucial for stable augmentations.
• Eye-tracking and gaze estimation enable foveated rendering and UI interaction; require calibration and privacy controls.
• IMU drift, magnetometer interference, and lighting conditions affect reliability — plan sensor fusion and error recovery.

5. Performance & latency

• Motion-to-photon latency should be very low (<20–50 ms target) to avoid motion sickness and maintain presence.
• GPU/compute choices affect resolution, frame rate, and thermal constraints.
• Consider foveated rendering and hardware acceleration to reduce processing load.

6. Ergonomics & industrial design

• Weight distribution, balance, and center of gravity matter more than total weight.
• Materials, fit options (prescription inserts, nose pads), and adjustability affect adoption.
• Heat management: thermal throttling and hot spots are user experience risks.

7. Power & battery

• Battery life targets depend on use case (all-day enterprise vs. 1–3 hours consumer).
• Trade-offs between onboard battery (heavier) and tethering to a belt pack.
• Fast charging and modular/replaceable batteries can be differentiators.

8. Software platform & developer ecosystem

• SDKs, APIs, and standards (WebXR, ARCore/ARKit alternatives) determine third‑party app availability.
• Tooling for content creation (3D assets, UI libraries) reduces developer friction.
• Backwards compatibility and update strategy for long-lived hardware.

9. User interface & interaction

• Interaction models: gesture, voice, touchpad, controller, eye gaze — choose based on environment and accessibility.
• Spatial UI design: avoid clutter, use depth and anchors, consider occlusion with real objects.
• Accessibility features (voice, captioning, high-contrast overlays) are important for inclusivity.

10. Privacy, security & ethics

• Camera, microphone, and eye-tracking raise privacy concerns—provide clear indicators, consent flows, and local-data controls.
• Secure boot, encrypted storage, and permissioning prevent misuse.
• Consider legal/regulatory constraints for recording in public and workplace monitoring.

11. Regulatory, safety & standards

• RF exposure, EMC, and product safety certifications vary by market.
• Optical safety (retinal exposure), driver-distraction rules, and workplace PPE standards may apply.

12. Manufacturing & modularity

• Serviceability (replaceable temples, batteries, lenses) reduces lifecycle cost.
• Custom prescription lens support, different frame sizes, and modular sensors enable customization at scale.
• Supply chain for specialized components (waveguides, custom optics) can be a bottleneck.

13. Testing & validation

• Real-world testing across lighting, motion, and edge cases (fog, reflections, sunglasses).
• Usability testing for comfort, fatigue, and cognitive load over extended wear.
• Automated QA for tracking stability, calibration drift, and recovery modes.

14. Cost & business model

• Component choices drive cost: optics and displays are major contributors.
• Consider subscription services, enterprise licensing, or hardware-as-a-service for high-cost devices.
• Upgrade paths and trade-in programs help users adopt new hardware.

15. Future-proofing & upgrades

• Modular hardware and over-the-air (OTA) firmware updates extend device life.
• Support for emerging standards (spatial web, mixed-reality formats) keeps content compatible.