The question is too generic. But let me try to provide some insights.
1. The organisation should have answers to the following questions:
- Why a new software is required for the organization
- What are the current challenges
- What are the business objectives
- What are the organization goals towards productivity
- etc.
2. Once you have answers, work on the list of challenges and objectives
3. Prepare existing (as-is) business process and scenarios. Document them in readable fomat (may be flow charts)
4. Document the as-si business rules
5. Organize a business process transformation workshop (if required). Discuss and finalize the new suggestions and chagnes in business processes (if any)
6. Document the to-be business process in readable format (may be flow chart)
7. Decide on an implementation methodology (agile/ waterfall / hybrid / others)
8. Plan your project depending on methoology
9. Organize the requirement elaboration workshops / product demonstration boot camps --> depending on your project methodology
10. Document the outcomes
11. Prepare requirement specification documents / user stories / epics --> depending on your project methoodology
12. Prepare basic design of the system, prepare system blue print, ERD, screenshots
13. Make end user familiar with the screens and processes
14. Prepare wore frame documentation / mockups and distribute among business users
15. Get agreement on design specification, wireframes
16. Breakdown your tasks in DevOps / TFS / Any other ALM tool you want to use
17. Onboard team based on the skill set required developer / integration specialist / QA / UI Developer
18. Plan your development practices
- Coding standards
- Naming conventions
- Create solution and add the required components
- Perform al configuration / configuration inside solution, so that deployment can be done properly.
- Maintain Development, SIT, UAT, Production as separate instance
19. Organise Conference room pilots and collect feedback
20. Organise Release / Sprint demos if you are in Agile
21. Release the system for users
22. Identify the data to be migrated and structure of the existing data (uyou can do this while requirement elaboration or designing the system)
23. Organise data transformation if required
24. Create data management strategy, data migration strategy, data migration approach
25. execute data migration