Major stages in new-product development process?

I would recommend you should read the below-mentioned blog for the best guidance and implementation.

However, there are 10 main stages that you should keep in mind

1. Idea Generation
2. Idea screening
3. Concept Testing
4. Product Prototype
5. External Refinement and Testing (Beta Test)
6. Perfect the Design and Prepare for Production
7. Prepare for Potential Issues and Solutions
8. Commercialization
9. Post Launch Activities
10. Review the Performance of New Product